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# Release Notes - ZooKeeper - Version 3.8.6

## Bug

* [ZOOKEEPER-4984](https://issues.apache.org/jira/browse/ZOOKEEPER-4984) - Upgrade OWASP plugin to 12.1.6 due to breaking changes in the API
* [ZOOKEEPER-4986](https://issues.apache.org/jira/browse/ZOOKEEPER-4986) - Disable reverse DNS lookup in TLS client and server

## Improvement

* [ZOOKEEPER-3938](https://issues.apache.org/jira/browse/ZOOKEEPER-3938) - Upgrade jline to version 3.x.

## Task

* [ZOOKEEPER-4976](https://issues.apache.org/jira/browse/ZOOKEEPER-4976) - Update Netty to fix CVE-2025-58057
* [ZOOKEEPER-5017](https://issues.apache.org/jira/browse/ZOOKEEPER-5017) - Upgrade Netty to 4.1.130.Final to address CVE-2025-67735
* [ZOOKEEPER-5018](https://issues.apache.org/jira/browse/ZOOKEEPER-5018) - Upgrade Jetty to 9.4.58.v20250814 in order to fix CVE-2025-5115


&nbsp;


# Release Notes - ZooKeeper - Version 3.8.5

## Breaking changes
[ZOOKEEPER-4891](https://issues.apache.org/jira/browse/ZOOKEEPER-4891) updates `logback-classic` to `1.3.15` to solve cve issues and
`slf4j-api` to `2.0.13` to meet compatibilty requirement of logback.

This could cause slf4j to complain "No SLF4J providers were found" and output no further logs in certain conditions.
1. For library or client usage, this could happen if you specify and inherit incompatible slf4j and logback versions, say, `slf4j-api:2.0.13` from
   `org.apache.zookeeper:zookeeper` and `logback-classic:1.2.13` from customized project dependencies.
2. For application or deployment usage, this could happen if you custom and inherit incompatible slf4j and logback versions in classpath, say,
   `slf4j-api:2.0.13` from zookeeper distribution and `logback-classic:1.2.13` from customization.

This could be solved by specifying compatiable slf4j and logback versions in classpath, say, `slf4j-api:2.0.13` and `logback-classic:1.3.15`.
                
## Bug

* [ZOOKEEPER-2623](https://issues.apache.org/jira/browse/ZOOKEEPER-2623) - CheckVersion outside of Multi causes NullPointerException
* [ZOOKEEPER-4293](https://issues.apache.org/jira/browse/ZOOKEEPER-4293) - Lock Contention in ClientCnxnSocketNetty (possible deadlock)
* [ZOOKEEPER-4604](https://issues.apache.org/jira/browse/ZOOKEEPER-4604) - Creating a COMPLETION_STRING_STAT would set acl_result completion
* [ZOOKEEPER-4752](https://issues.apache.org/jira/browse/ZOOKEEPER-4752) - Remove version files  in zookeeper-server/src/main from .gitignore
* [ZOOKEEPER-4787](https://issues.apache.org/jira/browse/ZOOKEEPER-4787) - Failed to establish connection between zookeeper
* [ZOOKEEPER-4843](https://issues.apache.org/jira/browse/ZOOKEEPER-4843) - Encountering an &#39;Unreasonable Length&#39; error when configuring jute.maxbuffer to 1GB or more
* [ZOOKEEPER-4846](https://issues.apache.org/jira/browse/ZOOKEEPER-4846) - Failure to reload database due to missing ACL
* [ZOOKEEPER-4876](https://issues.apache.org/jira/browse/ZOOKEEPER-4876) - jetty-http-9.4.53.v20231009.jar: CVE-2024-6763(3.7)
* [ZOOKEEPER-4886](https://issues.apache.org/jira/browse/ZOOKEEPER-4886) - observer with small myid can&#39;t join SASL quorum
* [ZOOKEEPER-4889](https://issues.apache.org/jira/browse/ZOOKEEPER-4889) - Fallback to DIGEST-MD5 auth mech should be disabled in Fips mode
* [ZOOKEEPER-4900](https://issues.apache.org/jira/browse/ZOOKEEPER-4900) - Bump patch release of jetty to include CVE fix for CVE-2024-6763
* [ZOOKEEPER-4909](https://issues.apache.org/jira/browse/ZOOKEEPER-4909) - When a spurious wakeup occurs, the client’s waiting time may exceed requestTimeout.
* [ZOOKEEPER-4919](https://issues.apache.org/jira/browse/ZOOKEEPER-4919) - ResponseCache supposed to be a LRU cache
* [ZOOKEEPER-4928](https://issues.apache.org/jira/browse/ZOOKEEPER-4928) - Version in zookeeper_version.h is not updated
* [ZOOKEEPER-4933](https://issues.apache.org/jira/browse/ZOOKEEPER-4933) - Connection throttle exception causing all connections to be rejected
* [ZOOKEEPER-4953](https://issues.apache.org/jira/browse/ZOOKEEPER-4953) - Fixing Typo In ZooKeeper Programmer&#39;s Guide
* [ZOOKEEPER-4960](https://issues.apache.org/jira/browse/ZOOKEEPER-4960) - Upgrade OWASP plugin to 12.1.3 due to recent parsing errors
                
## Improvement

* [ZOOKEEPER-3731](https://issues.apache.org/jira/browse/ZOOKEEPER-3731) - Disable HTTP TRACE Method
* [ZOOKEEPER-4546](https://issues.apache.org/jira/browse/ZOOKEEPER-4546) - Backport auto reloading client key/trust store to 3.8
* [ZOOKEEPER-4850](https://issues.apache.org/jira/browse/ZOOKEEPER-4850) - Enhance zkCli Tool to Support Reading and Writing Binary Data
* [ZOOKEEPER-4852](https://issues.apache.org/jira/browse/ZOOKEEPER-4852) - Fix the bad "*uuuuu" mark in the ASF license
* [ZOOKEEPER-4891](https://issues.apache.org/jira/browse/ZOOKEEPER-4891) - Update logback to 1.3.15 to fix CVE-2024-12798.
* [ZOOKEEPER-4902](https://issues.apache.org/jira/browse/ZOOKEEPER-4902) - Document that read-only mode also enables isro 4lw
* [ZOOKEEPER-4906](https://issues.apache.org/jira/browse/ZOOKEEPER-4906) - Log full exception details for server JAAS config failure
* [ZOOKEEPER-4944](https://issues.apache.org/jira/browse/ZOOKEEPER-4944) - Cache zookeeper dists for end to end compatibility tests
    
## Test

* [ZOOKEEPER-4480](https://issues.apache.org/jira/browse/ZOOKEEPER-4480) - Introduce end to end compatibility tests
* [ZOOKEEPER-4859](https://issues.apache.org/jira/browse/ZOOKEEPER-4859) - C client tests hang to be cancelled quite often
        
## Task

* [ZOOKEEPER-4679](https://issues.apache.org/jira/browse/ZOOKEEPER-4679) - Fix CI failure and warning
* [ZOOKEEPER-4868](https://issues.apache.org/jira/browse/ZOOKEEPER-4868) - Bump commons-io library to 2.14.0
* [ZOOKEEPER-4897](https://issues.apache.org/jira/browse/ZOOKEEPER-4897) - Upgrade Netty to fix CVE-2025-24970 in ZooKeeper 3.9.3
* [ZOOKEEPER-4959](https://issues.apache.org/jira/browse/ZOOKEEPER-4959) - Fix license files after logback/slf4j upgrade

&nbsp;


# Release Notes - ZooKeeper - Version 3.8.4

## Sub-task
* [ZOOKEEPER-910](https://issues.apache.org/jira/browse/ZOOKEEPER-910) - Use SelectionKey.isXYZ() methods instead of complicated binary logic
* [ZOOKEEPER-4728](https://issues.apache.org/jira/browse/ZOOKEEPER-4728) - Zookeepr cannot bind to itself forever if DNS is not ready when startup

## Bug
* [ZOOKEEPER-2590](https://issues.apache.org/jira/browse/ZOOKEEPER-2590) - exists() should check read ACL permission
* [ZOOKEEPER-4236](https://issues.apache.org/jira/browse/ZOOKEEPER-4236) - Java Client SendThread create many unnecessary Login objects
* [ZOOKEEPER-4758](https://issues.apache.org/jira/browse/ZOOKEEPER-4758) - Upgrade snappy-java to 1.1.10.4 to fix CVE-2023-43642
* [ZOOKEEPER-4762](https://issues.apache.org/jira/browse/ZOOKEEPER-4762) - Update netty jars to 4.1.99+ to fix CVE-2023-4586
* [ZOOKEEPER-4787](https://issues.apache.org/jira/browse/ZOOKEEPER-4787) - Failed to establish connection between zookeeper

## Improvement
* [ZOOKEEPER-4756](https://issues.apache.org/jira/browse/ZOOKEEPER-4756) - Merge script should use GitHub api to merge pull requests
* [ZOOKEEPER-4764](https://issues.apache.org/jira/browse/ZOOKEEPER-4764) - Tune the log of refuse session request.
* [ZOOKEEPER-4778](https://issues.apache.org/jira/browse/ZOOKEEPER-4778) - Patch jetty, netty, and logback to remove high severity vulnerabilities
* [ZOOKEEPER-4799](https://issues.apache.org/jira/browse/ZOOKEEPER-4799) - Refactor ACL check in addWatch command


&nbsp;


# Release Notes - ZooKeeper - Version 3.8.3

## Bug

* [ZOOKEEPER-4721](https://issues.apache.org/jira/browse/ZOOKEEPER-4721) - Upgrade OWASP Dependency Check to 8.3.1

## Improvement

* [ZOOKEEPER-4753](https://issues.apache.org/jira/browse/ZOOKEEPER-4753) - Explicit handling of DIGEST-MD5 vs GSSAPI in quorum auth

## Task

* [ZOOKEEPER-4751](https://issues.apache.org/jira/browse/ZOOKEEPER-4751) - Update snappy-java to 1.1.10.5 to address CVE-2023-43642
* [ZOOKEEPER-4754](https://issues.apache.org/jira/browse/ZOOKEEPER-4754) - Update Jetty to avoid CVE-2023-36479, CVE-2023-40167, and CVE-2023-41900
* [ZOOKEEPER-4755](https://issues.apache.org/jira/browse/ZOOKEEPER-4755) - Handle Netty CVE-2023-4586

&nbsp;


# Release Notes - ZooKeeper - Version 3.8.2

## Bug

* [ZOOKEEPER-4674](https://issues.apache.org/jira/browse/ZOOKEEPER-4674) - C client tests don&#39;t pass on CI
* [ZOOKEEPER-4647](https://issues.apache.org/jira/browse/ZOOKEEPER-4647) - Tests don&#39;t pass on JDK20 because we try to mock InetAddress
* [ZOOKEEPER-4026](https://issues.apache.org/jira/browse/ZOOKEEPER-4026) - CREATE2 requests embeded in a MULTI request only get a regular CREATE response
* [ZOOKEEPER-4393](https://issues.apache.org/jira/browse/ZOOKEEPER-4393) - Problem to connect to zookeeper in FIPS mode

## Improvement

* [ZOOKEEPER-3860](https://issues.apache.org/jira/browse/ZOOKEEPER-3860) - Avoid reverse DNS lookup for hostname verification when hostnames are provided in the connection url

## Task

* [ZOOKEEPER-4599](https://issues.apache.org/jira/browse/ZOOKEEPER-4599) - Upgrade Jetty to avoid CVE-2022-2048
* [ZOOKEEPER-4669](https://issues.apache.org/jira/browse/ZOOKEEPER-4669) - Upgrade snappy-java to 1.1.9.1 in order to support M1 macs
* [ZOOKEEPER-4688](https://issues.apache.org/jira/browse/ZOOKEEPER-4688) - Upgrade cyclonedx-maven-plugin to 2.7.6
* [ZOOKEEPER-4700](https://issues.apache.org/jira/browse/ZOOKEEPER-4700) - Update Jetty for fixing CVE-2023-26048 and CVE-2023-26049
* [ZOOKEEPER-4707](https://issues.apache.org/jira/browse/ZOOKEEPER-4707) - Update snappy-java to address multiple CVEs
* [ZOOKEEPER-4709](https://issues.apache.org/jira/browse/ZOOKEEPER-4709) - Upgrade Netty to 4.1.94.Final
* [ZOOKEEPER-4716](https://issues.apache.org/jira/browse/ZOOKEEPER-4716) - Upgrade jackson to 2.15.2 and suppress two false positive CVE errors



# Release Notes - ZooKeeper - Version 3.8.1

## Bug

* [ZOOKEEPER-3652](https://issues.apache.org/jira/browse/ZOOKEEPER-3652) - Improper synchronization in ClientCnxn
* [ZOOKEEPER-4308](https://issues.apache.org/jira/browse/ZOOKEEPER-4308) - Flaky test: EagerACLFilterTest.testSetDataFail
* [ZOOKEEPER-4460](https://issues.apache.org/jira/browse/ZOOKEEPER-4460) - QuorumPeer overrides Thread.getId with different semantics
* [ZOOKEEPER-4473](https://issues.apache.org/jira/browse/ZOOKEEPER-4473) - zooInspector create root node fail with path validate
* [ZOOKEEPER-4477](https://issues.apache.org/jira/browse/ZOOKEEPER-4477) - Single Kerberos ticket renewal failure can prevent all future renewals since Java 9
* [ZOOKEEPER-4504](https://issues.apache.org/jira/browse/ZOOKEEPER-4504) - ZKUtil#deleteRecursive causing deadlock in HDFS HA functionality
* [ZOOKEEPER-4505](https://issues.apache.org/jira/browse/ZOOKEEPER-4505) - CVE-2020-36518 - Upgrade jackson databind to 2.13.2.1
* [ZOOKEEPER-4511](https://issues.apache.org/jira/browse/ZOOKEEPER-4511) - Flaky test: FileTxnSnapLogMetricsTest.testFileTxnSnapLogMetrics
* [ZOOKEEPER-4514](https://issues.apache.org/jira/browse/ZOOKEEPER-4514) - ClientCnxnSocketNetty throwing NPE
* [ZOOKEEPER-4515](https://issues.apache.org/jira/browse/ZOOKEEPER-4515) - ZK Cli quit command always logs error
* [ZOOKEEPER-4537](https://issues.apache.org/jira/browse/ZOOKEEPER-4537) - Race between SyncThread and CommitProcessor thread
* [ZOOKEEPER-4654](https://issues.apache.org/jira/browse/ZOOKEEPER-4654) - Fix C client test compilation error in Util.cc.

## Improvement

* [ZOOKEEPER-4289](https://issues.apache.org/jira/browse/ZOOKEEPER-4289) - Reduce the performance impact of Prometheus metrics
* [ZOOKEEPER-4529](https://issues.apache.org/jira/browse/ZOOKEEPER-4529) - Upgrade netty to 4.1.76.Final
* [ZOOKEEPER-4531](https://issues.apache.org/jira/browse/ZOOKEEPER-4531) - Revert Netty TCNative change
* [ZOOKEEPER-4551](https://issues.apache.org/jira/browse/ZOOKEEPER-4551) - Do not log spammy stacktrace when a client closes its connection
* [ZOOKEEPER-4616](https://issues.apache.org/jira/browse/ZOOKEEPER-4616) - Upgrade docker image for the dev enviroment to resolve CVEs
* [ZOOKEEPER-4657](https://issues.apache.org/jira/browse/ZOOKEEPER-4657) - Publish SBOM artifacts
* [ZOOKEEPER-4659](https://issues.apache.org/jira/browse/ZOOKEEPER-4659) - Upgrade Commons CLI to 1.5.0 due to OWASP failing on 1.4 CVE-2021-37533
* [ZOOKEEPER-4660](https://issues.apache.org/jira/browse/ZOOKEEPER-4660) - Suppress false positive OWASP failure for CVE-2021-37533
* [ZOOKEEPER-4661](https://issues.apache.org/jira/browse/ZOOKEEPER-4661) - Upgrade Jackson Databind to 2.13.4.2 for CVE-2022-42003 CVE-2022-42004

## Task

* [ZOOKEEPER-4479](https://issues.apache.org/jira/browse/ZOOKEEPER-4479) - Tests: C client test TestOperations.cc testTimeoutCausedByWatches1 is very flaky on CI
* [ZOOKEEPER-4510](https://issues.apache.org/jira/browse/ZOOKEEPER-4510) - dependency-check:check failing - reload4j-1.2.19.jar: CVE-2020-9493, CVE-2022-23307
* [ZOOKEEPER-4627](https://issues.apache.org/jira/browse/ZOOKEEPER-4627) - High CVE-2022-2048 in jetty-*-9.4.46.v20220331.jar fixed in 9.4.47
* [ZOOKEEPER-4632](https://issues.apache.org/jira/browse/ZOOKEEPER-4632) - Fix NPE from ConnectionMetricsTest.testRevalidateCount
* [ZOOKEEPER-4641](https://issues.apache.org/jira/browse/ZOOKEEPER-4641) - GH CI fails with error: implicit declaration of function FIPS_mode
* [ZOOKEEPER-4649](https://issues.apache.org/jira/browse/ZOOKEEPER-4649) - Upgrade netty to 4.1.86 because of CVE-2022-41915
* [ZOOKEEPER-4666](https://issues.apache.org/jira/browse/ZOOKEEPER-4666) - Fix license files for Netty: some files are for 4.1.76 and some other files are for 4.1.86

## Sub-task

* [ZOOKEEPER-4327](https://issues.apache.org/jira/browse/ZOOKEEPER-4327) - Flaky test: RequestThrottlerTest


&nbsp;

# Release Notes - ZooKeeper - Version 3.8.0

    
## New Feature

* [ZOOKEEPER-3301](https://issues.apache.org/jira/browse/ZOOKEEPER-3301) - Enforce the quota limit
* [ZOOKEEPER-3601](https://issues.apache.org/jira/browse/ZOOKEEPER-3601) - introduce the fault injection framework: Byteman for ZooKeeper
* [ZOOKEEPER-3907](https://issues.apache.org/jira/browse/ZOOKEEPER-3907) - add a documentation about alerting on metrics
* [ZOOKEEPER-4211](https://issues.apache.org/jira/browse/ZOOKEEPER-4211) - Expose Quota Metrics to Prometheus

##  Improvement

* [ZOOKEEPER-1871](https://issues.apache.org/jira/browse/ZOOKEEPER-1871) - Add an option to zkCli to wait for connection before executing commands
* [ZOOKEEPER-2907](https://issues.apache.org/jira/browse/ZOOKEEPER-2907) - Logged request buffer isn&#39;t useful
* [ZOOKEEPER-3730](https://issues.apache.org/jira/browse/ZOOKEEPER-3730) - fix a typo about watchManagerName in the zookeeperAdmin.md
* [ZOOKEEPER-3798](https://issues.apache.org/jira/browse/ZOOKEEPER-3798) - remove the useless code in the ProposalRequestProcessor#processRequest
* [ZOOKEEPER-3800](https://issues.apache.org/jira/browse/ZOOKEEPER-3800) - improve the log printing the address when QuorumCnxManager#ListenerHandler&#39;s port binds
* [ZOOKEEPER-3807](https://issues.apache.org/jira/browse/ZOOKEEPER-3807) - fix the bad format when website pages build due to bash marker
* [ZOOKEEPER-3841](https://issues.apache.org/jira/browse/ZOOKEEPER-3841) - remove useless codes in the Leader.java
* [ZOOKEEPER-3849](https://issues.apache.org/jira/browse/ZOOKEEPER-3849) - improve the all logs with a necessary time unit at the start up of server
* [ZOOKEEPER-3898](https://issues.apache.org/jira/browse/ZOOKEEPER-3898) - Fix typos
* [ZOOKEEPER-3942](https://issues.apache.org/jira/browse/ZOOKEEPER-3942) - move traceMask calculation logic into the trace log guard
* [ZOOKEEPER-3961](https://issues.apache.org/jira/browse/ZOOKEEPER-3961) - Inaccurate Error Message
* [ZOOKEEPER-4001](https://issues.apache.org/jira/browse/ZOOKEEPER-4001) - AuditHelper.addAuditLog(...) more readable
* [ZOOKEEPER-4037](https://issues.apache.org/jira/browse/ZOOKEEPER-4037) - Closing autoCloseable resource with try-with-resources block
* [ZOOKEEPER-4046](https://issues.apache.org/jira/browse/ZOOKEEPER-4046) - Fix typo
* [ZOOKEEPER-4058](https://issues.apache.org/jira/browse/ZOOKEEPER-4058) - Update checkstyle-strict.xml by the latest version 8.39 of checkstyle
* [ZOOKEEPER-4188](https://issues.apache.org/jira/browse/ZOOKEEPER-4188) - add a doc about whoami CLI
* [ZOOKEEPER-4209](https://issues.apache.org/jira/browse/ZOOKEEPER-4209) - Update Netty version to 4.1.53.Final on 3.5 branch
* [ZOOKEEPER-4217](https://issues.apache.org/jira/browse/ZOOKEEPER-4217) - Report caller function name in `handle_socket_error_msg`
* [ZOOKEEPER-4231](https://issues.apache.org/jira/browse/ZOOKEEPER-4231) - Add document for snapshot compression config
* [ZOOKEEPER-4259](https://issues.apache.org/jira/browse/ZOOKEEPER-4259) - Allow AdminServer to force https
* [ZOOKEEPER-4280](https://issues.apache.org/jira/browse/ZOOKEEPER-4280) - fix the log format in the DataTree#deserializeZxidDigest method
* [ZOOKEEPER-4281](https://issues.apache.org/jira/browse/ZOOKEEPER-4281) - Packet length sanity check is inconsistent
* [ZOOKEEPER-4284](https://issues.apache.org/jira/browse/ZOOKEEPER-4284) - Add metrics for observer sync time
* [ZOOKEEPER-4291](https://issues.apache.org/jira/browse/ZOOKEEPER-4291) - ZooInspector has very high latency when operating against remote clusters
* [ZOOKEEPER-4294](https://issues.apache.org/jira/browse/ZOOKEEPER-4294) - FileSnap#findNValidSnapshots should not declare IOException
* [ZOOKEEPER-4301](https://issues.apache.org/jira/browse/ZOOKEEPER-4301) - fix typo
* [ZOOKEEPER-4312](https://issues.apache.org/jira/browse/ZOOKEEPER-4312) - ZooKeeperServerEmbedded: enhance server start/stop for testability
* [ZOOKEEPER-4318](https://issues.apache.org/jira/browse/ZOOKEEPER-4318) - Only report the follower sync time metrics if sync is completed
* [ZOOKEEPER-4326](https://issues.apache.org/jira/browse/ZOOKEEPER-4326) - fix typo in the recipes.md
* [ZOOKEEPER-4346](https://issues.apache.org/jira/browse/ZOOKEEPER-4346) - remove never used field
* [ZOOKEEPER-4349](https://issues.apache.org/jira/browse/ZOOKEEPER-4349) - delete the useless oraclePath directory generated by test suit
* [ZOOKEEPER-4350](https://issues.apache.org/jira/browse/ZOOKEEPER-4350) - improve the method: QuorumOracleMaj#overrideQuorumDecision
* [ZOOKEEPER-4355](https://issues.apache.org/jira/browse/ZOOKEEPER-4355) - ZK documentation side bar and welcome page are out of sync
* [ZOOKEEPER-4370](https://issues.apache.org/jira/browse/ZOOKEEPER-4370) - add zookeeperOracleQuorums.html link to webpage index
* [ZOOKEEPER-4380](https://issues.apache.org/jira/browse/ZOOKEEPER-4380) - Avoid NPE in RateLogger#rateLimitLog
* [ZOOKEEPER-4382](https://issues.apache.org/jira/browse/ZOOKEEPER-4382) - Update Maven Bundle Plugin in order to allow builds on JDK18
* [ZOOKEEPER-4396](https://issues.apache.org/jira/browse/ZOOKEEPER-4396) - Read Key/trust store password from file
* [ZOOKEEPER-4402](https://issues.apache.org/jira/browse/ZOOKEEPER-4402) - Added Hyperlink At LOGO
* [ZOOKEEPER-4411](https://issues.apache.org/jira/browse/ZOOKEEPER-4411) - improve the grammar issue[patch] in the README.md
* [ZOOKEEPER-4427](https://issues.apache.org/jira/browse/ZOOKEEPER-4427) - Migrate to Logback
* [ZOOKEEPER-4435](https://issues.apache.org/jira/browse/ZOOKEEPER-4435) - Typo in the log message of ServerCnxnFactory
* [ZOOKEEPER-4453](https://issues.apache.org/jira/browse/ZOOKEEPER-4453) - NettyServerCnxnFactory: allow to configure the early TLS connection drop feature
* [ZOOKEEPER-4454](https://issues.apache.org/jira/browse/ZOOKEEPER-4454) - Upgrade Netty to 4.1.73
* [ZOOKEEPER-4462](https://issues.apache.org/jira/browse/ZOOKEEPER-4462) - Upgrade Netty TCNative to 2.0.48

## Bug

* [ZOOKEEPER-3128](https://issues.apache.org/jira/browse/ZOOKEEPER-3128) - Get CLI Command displays Authentication error for Authorization error
* [ZOOKEEPER-3706](https://issues.apache.org/jira/browse/ZOOKEEPER-3706) - ZooKeeper.close() would leak SendThread when the network is broken
* [ZOOKEEPER-3781](https://issues.apache.org/jira/browse/ZOOKEEPER-3781) - Zookeeper 3.5.7 not creating snapshot
* [ZOOKEEPER-3877](https://issues.apache.org/jira/browse/ZOOKEEPER-3877) - JMX Bean RemotePeerBean should enclose IPV6 host in square bracket same as LocalPeerBean 
* [ZOOKEEPER-3887](https://issues.apache.org/jira/browse/ZOOKEEPER-3887) - In SSL-only server zkServer.sh status command should use secureClientPortAddress instead of clientPortAddress
* [ZOOKEEPER-3943](https://issues.apache.org/jira/browse/ZOOKEEPER-3943) - Zookeeper Inspector throwing NullPointerExceptions and not displaying properly
* [ZOOKEEPER-3987](https://issues.apache.org/jira/browse/ZOOKEEPER-3987) - Build failures when running surefire tests concurrently due to bind address already in use
* [ZOOKEEPER-3988](https://issues.apache.org/jira/browse/ZOOKEEPER-3988) - org.apache.zookeeper.server.NettyServerCnxn.receiveMessage throws NullPointerException
* [ZOOKEEPER-3992](https://issues.apache.org/jira/browse/ZOOKEEPER-3992) - addWatch api should check the null watch
* [ZOOKEEPER-4007](https://issues.apache.org/jira/browse/ZOOKEEPER-4007) - A typo in the ZKUtil#validateFileInput method
* [ZOOKEEPER-4050](https://issues.apache.org/jira/browse/ZOOKEEPER-4050) - Zookeeper Inspector reports &quot;List of default node viewers is empty&quot; when not specifically run from the zookeeper-contrib/zookeeper-contrib-zooinspector directory
* [ZOOKEEPER-4191](https://issues.apache.org/jira/browse/ZOOKEEPER-4191) - Missing executable bits in source release tarball
* [ZOOKEEPER-4194](https://issues.apache.org/jira/browse/ZOOKEEPER-4194) - ZooInspector throws NullPointerExceptions to console when node data is null
* [ZOOKEEPER-4201](https://issues.apache.org/jira/browse/ZOOKEEPER-4201) - C client: SASL-related compilation issues on macOS Catalina
* [ZOOKEEPER-4204](https://issues.apache.org/jira/browse/ZOOKEEPER-4204) - Flaky test - RequestPathMetricsCollectorTest.testMultiThreadPerf
* [ZOOKEEPER-4205](https://issues.apache.org/jira/browse/ZOOKEEPER-4205) - Test fails when port 8080 is in use
* [ZOOKEEPER-4207](https://issues.apache.org/jira/browse/ZOOKEEPER-4207) - New CI pipeline checks out master in branch builds too
* [ZOOKEEPER-4210](https://issues.apache.org/jira/browse/ZOOKEEPER-4210) - Zookeeper c client: detect connection loss during opportunistic async send
* [ZOOKEEPER-4219](https://issues.apache.org/jira/browse/ZOOKEEPER-4219) - Quota checks break setData in multi transactions
* [ZOOKEEPER-4220](https://issues.apache.org/jira/browse/ZOOKEEPER-4220) - Potential redundant connection attempts during leader election
* [ZOOKEEPER-4230](https://issues.apache.org/jira/browse/ZOOKEEPER-4230) - Use dynamic temp folder instead of static temp folder in RestMain
* [ZOOKEEPER-4232](https://issues.apache.org/jira/browse/ZOOKEEPER-4232) - InvalidSnapshotTest corrupts its own test data
* [ZOOKEEPER-4247](https://issues.apache.org/jira/browse/ZOOKEEPER-4247) - NPE while processing message from restarted quorum member
* [ZOOKEEPER-4265](https://issues.apache.org/jira/browse/ZOOKEEPER-4265) - Download page broken links
* [ZOOKEEPER-4266](https://issues.apache.org/jira/browse/ZOOKEEPER-4266) - Correct ZooKeeper version in documentation header
* [ZOOKEEPER-4267](https://issues.apache.org/jira/browse/ZOOKEEPER-4267) - Fix check-style issues
* [ZOOKEEPER-4269](https://issues.apache.org/jira/browse/ZOOKEEPER-4269) - acceptedEpoch.tmp rename failure will cause server startup error
* [ZOOKEEPER-4272](https://issues.apache.org/jira/browse/ZOOKEEPER-4272) - Upgrade Netty library to &gt; 4.1.60 due to security vulnerability CVE-2021-21295
* [ZOOKEEPER-4275](https://issues.apache.org/jira/browse/ZOOKEEPER-4275) - Slowness in sasl login or subject.doAs() causes zk client to falsely assume that the server did not respond, closes connection and goes to unnecessary retries
* [ZOOKEEPER-4277](https://issues.apache.org/jira/browse/ZOOKEEPER-4277) - dependency-check:check failing - jetty-server-9.4.38 CVE-2021-28165
* [ZOOKEEPER-4278](https://issues.apache.org/jira/browse/ZOOKEEPER-4278) - dependency-check:check failing - netty-transport-4.1.60.Final CVE-2021-21409 
* [ZOOKEEPER-4309](https://issues.apache.org/jira/browse/ZOOKEEPER-4309) - QuorumCnxManager&#39;s ListenerHandler thread leak
* [ZOOKEEPER-4311](https://issues.apache.org/jira/browse/ZOOKEEPER-4311) - Fsync errors are ignored in AtomicFileWritingIdiom
* [ZOOKEEPER-4325](https://issues.apache.org/jira/browse/ZOOKEEPER-4325) - IllegalArgumentException when use ZkUtil::listSubTreeBFS to list &quot;/&quot;
* [ZOOKEEPER-4337](https://issues.apache.org/jira/browse/ZOOKEEPER-4337) - CVE-2021-34429 in jetty 9.4.38.v20210224 in zookeeper 3.7.0
* [ZOOKEEPER-4342](https://issues.apache.org/jira/browse/ZOOKEEPER-4342) - Robustify C client against errors during SASL negotiation
* [ZOOKEEPER-4343](https://issues.apache.org/jira/browse/ZOOKEEPER-4343) - OWASP Dependency-Check fails with CVE-2021-29425, commons-io-2.6
* [ZOOKEEPER-4345](https://issues.apache.org/jira/browse/ZOOKEEPER-4345) - Avoid NoSunchMethodException caused by shaded zookeeper jar
* [ZOOKEEPER-4356](https://issues.apache.org/jira/browse/ZOOKEEPER-4356) - Code blocks do not render correctly in ZK docs site
* [ZOOKEEPER-4360](https://issues.apache.org/jira/browse/ZOOKEEPER-4360) - Avoid NPE during metrics execution if the leader is not set on a FOLLOWER node 
* [ZOOKEEPER-4362](https://issues.apache.org/jira/browse/ZOOKEEPER-4362) - ZKDatabase.txnCount logged non transactional requests
* [ZOOKEEPER-4367](https://issues.apache.org/jira/browse/ZOOKEEPER-4367) - Zookeeper#Login thread leak in case of Sasl AuthFailed.
* [ZOOKEEPER-4372](https://issues.apache.org/jira/browse/ZOOKEEPER-4372) - Zookeeper lock recipe doesn&#39;t parse negative sequence numbers correctly
* [ZOOKEEPER-4377](https://issues.apache.org/jira/browse/ZOOKEEPER-4377) - KeeperException.create has NullPointerException when low version client requests the high version server
* [ZOOKEEPER-4406](https://issues.apache.org/jira/browse/ZOOKEEPER-4406) - fix the znode type for Barrier implementation in the zookeeperTutorial.md

##  Test

* [ZOOKEEPER-4319](https://issues.apache.org/jira/browse/ZOOKEEPER-4319) - Refactor AtomicFileWritingIdiomTest to use TempDir annotation
* [ZOOKEEPER-4333](https://issues.apache.org/jira/browse/ZOOKEEPER-4333) - QuorumSSLTest - testOCSP fails on JDK17
* [ZOOKEEPER-4340](https://issues.apache.org/jira/browse/ZOOKEEPER-4340) - Add tab unit test for StringUtils#split
 
## Task

* [ZOOKEEPER-3957](https://issues.apache.org/jira/browse/ZOOKEEPER-3957) - Create Owasp check build on new Jenkins instance
* [ZOOKEEPER-3970](https://issues.apache.org/jira/browse/ZOOKEEPER-3970) - Enable ZooKeeperServerController to expire session
* [ZOOKEEPER-3980](https://issues.apache.org/jira/browse/ZOOKEEPER-3980) - Fix Jenkinsfiles with new tool names
* [ZOOKEEPER-4233](https://issues.apache.org/jira/browse/ZOOKEEPER-4233) - dependency-check:check failing - Jetty 9.4.35.v20201120 - CVE-2020-27223
* [ZOOKEEPER-4315](https://issues.apache.org/jira/browse/ZOOKEEPER-4315) - Fix NOTICE file in the source distribution
* [ZOOKEEPER-4384](https://issues.apache.org/jira/browse/ZOOKEEPER-4384) - Fix &#39;se[r]ver&#39; typo in ClientCnxn class.
* [ZOOKEEPER-4414](https://issues.apache.org/jira/browse/ZOOKEEPER-4414) - Update Netty to 4.1.70.Final
* [ZOOKEEPER-4429](https://issues.apache.org/jira/browse/ZOOKEEPER-4429) - Update jackson-databind to 2.13.1
* [ZOOKEEPER-4465](https://issues.apache.org/jira/browse/ZOOKEEPER-4465) - zooinspector logback pattern config add escape for '(' and ')'
* [ZOOKEEPER-4469](https://issues.apache.org/jira/browse/ZOOKEEPER-4469) - Suppress OWASP false positives related to Netty TCNative
* [ZOOKEEPER-4478](https://issues.apache.org/jira/browse/ZOOKEEPER-4479) - Suppress OWASP false positives zookeeper-jute-3.8.0-SNAPSHOT.jar: CVE-2021-29425, CVE-2021-28164, CVE-2021-34429








## Sub-task

* [ZOOKEEPER-3774](https://issues.apache.org/jira/browse/ZOOKEEPER-3774) - Close quorum socket asynchronously on the leader to avoid ping being blocked by long socket closing time
* [ZOOKEEPER-4251](https://issues.apache.org/jira/browse/ZOOKEEPER-4251) - Flaky test: org.apache.zookeeper.test.WatcherTest
* [ZOOKEEPER-4257](https://issues.apache.org/jira/browse/ZOOKEEPER-4257) - learner.asyncSending, learner.closeSocketAsync and leader.closeSocketAsync should be configurable in zoo.cfg
* [ZOOKEEPER-4270](https://issues.apache.org/jira/browse/ZOOKEEPER-4270) - Flaky test: QuorumPeerMainTest#testLeaderOutOfView
* [ZOOKEEPER-4461](https://issues.apache.org/jira/browse/ZOOKEEPER-4461) - Migrate zookeeper-contrib and -recipes projects.
            
## Bug

* [ZOOKEEPER-3128](https://issues.apache.org/jira/browse/ZOOKEEPER-3128) - Get CLI Command displays Authentication error for Authorization error
* [ZOOKEEPER-3706](https://issues.apache.org/jira/browse/ZOOKEEPER-3706) - ZooKeeper.close() would leak SendThread when the network is broken
* [ZOOKEEPER-3781](https://issues.apache.org/jira/browse/ZOOKEEPER-3781) - Zookeeper 3.5.7 not creating snapshot
* [ZOOKEEPER-3877](https://issues.apache.org/jira/browse/ZOOKEEPER-3877) - JMX Bean RemotePeerBean should enclose IPV6 host in square bracket same as LocalPeerBean 
* [ZOOKEEPER-3887](https://issues.apache.org/jira/browse/ZOOKEEPER-3887) - In SSL-only server zkServer.sh status command should use secureClientPortAddress instead of clientPortAddress
* [ZOOKEEPER-3943](https://issues.apache.org/jira/browse/ZOOKEEPER-3943) - Zookeeper Inspector throwing NullPointerExceptions and not displaying properly
* [ZOOKEEPER-3987](https://issues.apache.org/jira/browse/ZOOKEEPER-3987) - Build failures when running surefire tests concurrently due to bind address already in use
* [ZOOKEEPER-3988](https://issues.apache.org/jira/browse/ZOOKEEPER-3988) - org.apache.zookeeper.server.NettyServerCnxn.receiveMessage throws NullPointerException
* [ZOOKEEPER-3992](https://issues.apache.org/jira/browse/ZOOKEEPER-3992) - addWatch api should check the null watch
* [ZOOKEEPER-4007](https://issues.apache.org/jira/browse/ZOOKEEPER-4007) - A typo in the ZKUtil#validateFileInput method
* [ZOOKEEPER-4050](https://issues.apache.org/jira/browse/ZOOKEEPER-4050) - Zookeeper Inspector reports &quot;List of default node viewers is empty&quot; when not specifically run from the zookeeper-contrib/zookeeper-contrib-zooinspector directory
* [ZOOKEEPER-4191](https://issues.apache.org/jira/browse/ZOOKEEPER-4191) - Missing executable bits in source release tarball
* [ZOOKEEPER-4194](https://issues.apache.org/jira/browse/ZOOKEEPER-4194) - ZooInspector throws NullPointerExceptions to console when node data is null
* [ZOOKEEPER-4201](https://issues.apache.org/jira/browse/ZOOKEEPER-4201) - C client: SASL-related compilation issues on macOS Catalina
* [ZOOKEEPER-4204](https://issues.apache.org/jira/browse/ZOOKEEPER-4204) - Flaky test - RequestPathMetricsCollectorTest.testMultiThreadPerf
* [ZOOKEEPER-4205](https://issues.apache.org/jira/browse/ZOOKEEPER-4205) - Test fails when port 8080 is in use
* [ZOOKEEPER-4207](https://issues.apache.org/jira/browse/ZOOKEEPER-4207) - New CI pipeline checks out master in branch builds too
* [ZOOKEEPER-4210](https://issues.apache.org/jira/browse/ZOOKEEPER-4210) - Zookeeper c client: detect connection loss during opportunistic async send
* [ZOOKEEPER-4219](https://issues.apache.org/jira/browse/ZOOKEEPER-4219) - Quota checks break setData in multi transactions
* [ZOOKEEPER-4220](https://issues.apache.org/jira/browse/ZOOKEEPER-4220) - Potential redundant connection attempts during leader election
* [ZOOKEEPER-4230](https://issues.apache.org/jira/browse/ZOOKEEPER-4230) - Use dynamic temp folder instead of static temp folder in RestMain
* [ZOOKEEPER-4232](https://issues.apache.org/jira/browse/ZOOKEEPER-4232) - InvalidSnapshotTest corrupts its own test data
* [ZOOKEEPER-4247](https://issues.apache.org/jira/browse/ZOOKEEPER-4247) - NPE while processing message from restarted quorum member
* [ZOOKEEPER-4265](https://issues.apache.org/jira/browse/ZOOKEEPER-4265) - Download page broken links
* [ZOOKEEPER-4266](https://issues.apache.org/jira/browse/ZOOKEEPER-4266) - Correct ZooKeeper version in documentation header
* [ZOOKEEPER-4267](https://issues.apache.org/jira/browse/ZOOKEEPER-4267) - Fix check-style issues
* [ZOOKEEPER-4269](https://issues.apache.org/jira/browse/ZOOKEEPER-4269) - acceptedEpoch.tmp rename failure will cause server startup error
* [ZOOKEEPER-4272](https://issues.apache.org/jira/browse/ZOOKEEPER-4272) - Upgrade Netty library to &gt; 4.1.60 due to security vulnerability CVE-2021-21295
* [ZOOKEEPER-4275](https://issues.apache.org/jira/browse/ZOOKEEPER-4275) - Slowness in sasl login or subject.doAs() causes zk client to falsely assume that the server did not respond, closes connection and goes to unnecessary retries
* [ZOOKEEPER-4277](https://issues.apache.org/jira/browse/ZOOKEEPER-4277) - dependency-check:check failing - jetty-server-9.4.38 CVE-2021-28165
* [ZOOKEEPER-4278](https://issues.apache.org/jira/browse/ZOOKEEPER-4278) - dependency-check:check failing - netty-transport-4.1.60.Final CVE-2021-21409 
* [ZOOKEEPER-4309](https://issues.apache.org/jira/browse/ZOOKEEPER-4309) - QuorumCnxManager&#39;s ListenerHandler thread leak
* [ZOOKEEPER-4311](https://issues.apache.org/jira/browse/ZOOKEEPER-4311) - Fsync errors are ignored in AtomicFileWritingIdiom
* [ZOOKEEPER-4325](https://issues.apache.org/jira/browse/ZOOKEEPER-4325) - IllegalArgumentException when use ZkUtil::listSubTreeBFS to list &quot;/&quot;
* [ZOOKEEPER-4337](https://issues.apache.org/jira/browse/ZOOKEEPER-4337) - CVE-2021-34429 in jetty 9.4.38.v20210224 in zookeeper 3.7.0
* [ZOOKEEPER-4342](https://issues.apache.org/jira/browse/ZOOKEEPER-4342) - Robustify C client against errors during SASL negotiation
* [ZOOKEEPER-4343](https://issues.apache.org/jira/browse/ZOOKEEPER-4343) - OWASP Dependency-Check fails with CVE-2021-29425, commons-io-2.6
* [ZOOKEEPER-4345](https://issues.apache.org/jira/browse/ZOOKEEPER-4345) - Avoid NoSunchMethodException caused by shaded zookeeper jar
* [ZOOKEEPER-4356](https://issues.apache.org/jira/browse/ZOOKEEPER-4356) - Code blocks do not render correctly in ZK docs site
* [ZOOKEEPER-4360](https://issues.apache.org/jira/browse/ZOOKEEPER-4360) - Avoid NPE during metrics execution if the leader is not set on a FOLLOWER node 
* [ZOOKEEPER-4362](https://issues.apache.org/jira/browse/ZOOKEEPER-4362) - ZKDatabase.txnCount logged non transactional requests
* [ZOOKEEPER-4367](https://issues.apache.org/jira/browse/ZOOKEEPER-4367) - Zookeeper#Login thread leak in case of Sasl AuthFailed.
* [ZOOKEEPER-4372](https://issues.apache.org/jira/browse/ZOOKEEPER-4372) - Zookeeper lock recipe doesn&#39;t parse negative sequence numbers correctly
* [ZOOKEEPER-4377](https://issues.apache.org/jira/browse/ZOOKEEPER-4377) - KeeperException.create has NullPointerException when low version client requests the high version server
* [ZOOKEEPER-4406](https://issues.apache.org/jira/browse/ZOOKEEPER-4406) - fix the znode type for Barrier implementation in the zookeeperTutorial.md

        
## New Feature

* [ZOOKEEPER-3301](https://issues.apache.org/jira/browse/ZOOKEEPER-3301) - Enforce the quota limit
* [ZOOKEEPER-3601](https://issues.apache.org/jira/browse/ZOOKEEPER-3601) - introduce the fault injection framework: Byteman for ZooKeeper
* [ZOOKEEPER-3907](https://issues.apache.org/jira/browse/ZOOKEEPER-3907) - add a documentation about alerting on metrics
* [ZOOKEEPER-4211](https://issues.apache.org/jira/browse/ZOOKEEPER-4211) - Expose Quota Metrics to Prometheus

        
##  Improvement

* [ZOOKEEPER-1871](https://issues.apache.org/jira/browse/ZOOKEEPER-1871) - Add an option to zkCli to wait for connection before executing commands
* [ZOOKEEPER-2907](https://issues.apache.org/jira/browse/ZOOKEEPER-2907) - Logged request buffer isn&#39;t useful
* [ZOOKEEPER-3730](https://issues.apache.org/jira/browse/ZOOKEEPER-3730) - fix a typo about watchManagerName in the zookeeperAdmin.md
* [ZOOKEEPER-3798](https://issues.apache.org/jira/browse/ZOOKEEPER-3798) - remove the useless code in the ProposalRequestProcessor#processRequest
* [ZOOKEEPER-3800](https://issues.apache.org/jira/browse/ZOOKEEPER-3800) - improve the log printing the address when QuorumCnxManager#ListenerHandler&#39;s port binds 
* [ZOOKEEPER-3807](https://issues.apache.org/jira/browse/ZOOKEEPER-3807) - fix the bad format when website pages build due to bash marker
* [ZOOKEEPER-3841](https://issues.apache.org/jira/browse/ZOOKEEPER-3841) - remove useless codes in the Leader.java
* [ZOOKEEPER-3849](https://issues.apache.org/jira/browse/ZOOKEEPER-3849) - improve the all logs with a necessary time unit at the start up of server
* [ZOOKEEPER-3898](https://issues.apache.org/jira/browse/ZOOKEEPER-3898) - Fix typos
* [ZOOKEEPER-3942](https://issues.apache.org/jira/browse/ZOOKEEPER-3942) - move traceMask calculation logic into the trace log guard
* [ZOOKEEPER-3961](https://issues.apache.org/jira/browse/ZOOKEEPER-3961) - Inaccurate Error Message
                                                                                                                                                   

# Release Notes - ZooKeeper - Version 3.7.0

## New Feature

* [ZOOKEEPER-1112](https://issues.apache.org/jira/browse/ZOOKEEPER-1112) - Add support for C client for SASL authentication
* [ZOOKEEPER-3264](https://issues.apache.org/jira/browse/ZOOKEEPER-3264) - The benchmark tools for zookeeper
* [ZOOKEEPER-3301](https://issues.apache.org/jira/browse/ZOOKEEPER-3301) - Enforce the quota limit
* [ZOOKEEPER-3681](https://issues.apache.org/jira/browse/ZOOKEEPER-3681) - Add s390x support for Travis build
* [ZOOKEEPER-3714](https://issues.apache.org/jira/browse/ZOOKEEPER-3714) - Add (Cyrus) SASL authentication support to Perl client
* [ZOOKEEPER-3874](https://issues.apache.org/jira/browse/ZOOKEEPER-3874) - Official API to start ZooKeeper server from Java
* [ZOOKEEPER-3948](https://issues.apache.org/jira/browse/ZOOKEEPER-3948) - Introduce a deterministic runtime behavior injection framework for ZooKeeperServer testing
* [ZOOKEEPER-3959](https://issues.apache.org/jira/browse/ZOOKEEPER-3959) - Allow multiple superUsers with SASL
* [ZOOKEEPER-3969](https://issues.apache.org/jira/browse/ZOOKEEPER-3969) - Add whoami  API and Cli command
* [ZOOKEEPER-4030](https://issues.apache.org/jira/browse/ZOOKEEPER-4030) - Optionally canonicalize host names in quorum SASL authentication

## Improvement

* [ZOOKEEPER-1871](https://issues.apache.org/jira/browse/ZOOKEEPER-1871) - Add an option to zkCli to wait for connection before executing commands
* [ZOOKEEPER-2272](https://issues.apache.org/jira/browse/ZOOKEEPER-2272) - Code clean up in ZooKeeperServer and KerberosName
* [ZOOKEEPER-2649](https://issues.apache.org/jira/browse/ZOOKEEPER-2649) - The ZooKeeper do not write in log session ID in which the client has been authenticated.
* [ZOOKEEPER-2779](https://issues.apache.org/jira/browse/ZOOKEEPER-2779) - Add option to not set ACL for reconfig node
* [ZOOKEEPER-3101](https://issues.apache.org/jira/browse/ZOOKEEPER-3101) - Add comment reminding users to add cases to zerror when adding values to ZOO_ERRORS
* [ZOOKEEPER-3342](https://issues.apache.org/jira/browse/ZOOKEEPER-3342) - Use StandardCharsets
* [ZOOKEEPER-3411](https://issues.apache.org/jira/browse/ZOOKEEPER-3411) - remove the deprecated CLI: ls2 and rmr
* [ZOOKEEPER-3427](https://issues.apache.org/jira/browse/ZOOKEEPER-3427) - Introduce SnapshotComparer that assists debugging with snapshots.
* [ZOOKEEPER-3482](https://issues.apache.org/jira/browse/ZOOKEEPER-3482) - SASL (Kerberos) Authentication with SSL for clients and Quorum
* [ZOOKEEPER-3561](https://issues.apache.org/jira/browse/ZOOKEEPER-3561) - Generalize target authentication scheme for ZooKeeper authentication enforcement.
* [ZOOKEEPER-3567](https://issues.apache.org/jira/browse/ZOOKEEPER-3567) - Add SSL support for the zk python client
* [ZOOKEEPER-3581](https://issues.apache.org/jira/browse/ZOOKEEPER-3581) - use factory design pattern to refactor ZooKeeperMain
* [ZOOKEEPER-3582](https://issues.apache.org/jira/browse/ZOOKEEPER-3582) - refactor the async api call to lambda style
* [ZOOKEEPER-3638](https://issues.apache.org/jira/browse/ZOOKEEPER-3638) - Update Jetty to 9.4.24.v20191120
* [ZOOKEEPER-3640](https://issues.apache.org/jira/browse/ZOOKEEPER-3640) - Implement &quot;batch mode&quot; in cli_mt
* [ZOOKEEPER-3649](https://issues.apache.org/jira/browse/ZOOKEEPER-3649) - ls -s CLI need a line break
* [ZOOKEEPER-3662](https://issues.apache.org/jira/browse/ZOOKEEPER-3662) - Remove NPE Possibility in Follower Class
* [ZOOKEEPER-3663](https://issues.apache.org/jira/browse/ZOOKEEPER-3663) - Clean Up ZNodeName Class
* [ZOOKEEPER-3666](https://issues.apache.org/jira/browse/ZOOKEEPER-3666) - remove the deprecated LogFormatter tool
* [ZOOKEEPER-3671](https://issues.apache.org/jira/browse/ZOOKEEPER-3671) - Use ThreadLocalConcurrent to Replace Random and Math.random
* [ZOOKEEPER-3678](https://issues.apache.org/jira/browse/ZOOKEEPER-3678) - Remove Redundant GroupID from Maven POMs
* [ZOOKEEPER-3679](https://issues.apache.org/jira/browse/ZOOKEEPER-3679) - Upgrade maven-compiler-plugin For ZooKeeper-jute
* [ZOOKEEPER-3682](https://issues.apache.org/jira/browse/ZOOKEEPER-3682) - Stop initializing new SSL connection if ZK server is shutting down
* [ZOOKEEPER-3683](https://issues.apache.org/jira/browse/ZOOKEEPER-3683) - Discard requests that are delayed longer than a configured threshold
* [ZOOKEEPER-3687](https://issues.apache.org/jira/browse/ZOOKEEPER-3687) - Jute Use JDK hashCode Methods for Native Types
* [ZOOKEEPER-3688](https://issues.apache.org/jira/browse/ZOOKEEPER-3688) - Use StandardCharsets UTF-8 in Jute toString
* [ZOOKEEPER-3690](https://issues.apache.org/jira/browse/ZOOKEEPER-3690) - Improving leader efficiency via not processing learner&#39;s requests in commit processor
* [ZOOKEEPER-3691](https://issues.apache.org/jira/browse/ZOOKEEPER-3691) - Use JDK String Join Method in ZK StringUtils
* [ZOOKEEPER-3694](https://issues.apache.org/jira/browse/ZOOKEEPER-3694) - Use Map computeIfAbsent in AvgMinMaxCounterSet Class
* [ZOOKEEPER-3708](https://issues.apache.org/jira/browse/ZOOKEEPER-3708) - Move Logging Code into Logging Guard in Learner
* [ZOOKEEPER-3722](https://issues.apache.org/jira/browse/ZOOKEEPER-3722) - make logs of ResponseCache more readable
* [ZOOKEEPER-3728](https://issues.apache.org/jira/browse/ZOOKEEPER-3728) - move traceMask calculation logic into the trace log in the FinalRequestProcessor#processRequest
* [ZOOKEEPER-3741](https://issues.apache.org/jira/browse/ZOOKEEPER-3741) - Fix ZooKeeper 3.5 C client build on Fedora8
* [ZOOKEEPER-3761](https://issues.apache.org/jira/browse/ZOOKEEPER-3761) - upgrade JLine jar dependency
* [ZOOKEEPER-3767](https://issues.apache.org/jira/browse/ZOOKEEPER-3767) - fix a large amount of maven build warnings
* [ZOOKEEPER-3785](https://issues.apache.org/jira/browse/ZOOKEEPER-3785) - Make sources buildable with JDK14
* [ZOOKEEPER-3786](https://issues.apache.org/jira/browse/ZOOKEEPER-3786) - Simplify generation of VersionInfoMain and Info
* [ZOOKEEPER-3788](https://issues.apache.org/jira/browse/ZOOKEEPER-3788) - Add m2e configuration in pom.xml for Eclipse developers
* [ZOOKEEPER-3790](https://issues.apache.org/jira/browse/ZOOKEEPER-3790) - zkpython: Minor compilation and testing issues
* [ZOOKEEPER-3791](https://issues.apache.org/jira/browse/ZOOKEEPER-3791) - Miscellaneous Maven improvements
* [ZOOKEEPER-3796](https://issues.apache.org/jira/browse/ZOOKEEPER-3796) - Skip Learner Request made to ObserverMaster from going to next processor
* [ZOOKEEPER-3805](https://issues.apache.org/jira/browse/ZOOKEEPER-3805) - NIOServerCnxnFactory static block has no used code
* [ZOOKEEPER-3808](https://issues.apache.org/jira/browse/ZOOKEEPER-3808) - correct the documentation about digest.enabled
* [ZOOKEEPER-3811](https://issues.apache.org/jira/browse/ZOOKEEPER-3811) - cleaning up the code,A static field should be directly referred by its class name
* [ZOOKEEPER-3831](https://issues.apache.org/jira/browse/ZOOKEEPER-3831) - Add a test that does a minimal validation of Apache Curator
* [ZOOKEEPER-3833](https://issues.apache.org/jira/browse/ZOOKEEPER-3833) - Do Not Override Plugin Versions from Apache Parent POM
* [ZOOKEEPER-3836](https://issues.apache.org/jira/browse/ZOOKEEPER-3836) - Use Commons and JDK Functions in ClientBase
* [ZOOKEEPER-3839](https://issues.apache.org/jira/browse/ZOOKEEPER-3839) - ReconfigBackupTest Remove getFileContent
* [ZOOKEEPER-3883](https://issues.apache.org/jira/browse/ZOOKEEPER-3883) - new UncaughtExceptionHandler object with lambda
* [ZOOKEEPER-3893](https://issues.apache.org/jira/browse/ZOOKEEPER-3893) - Enhance documentation for property ssl.clientAuth
* [ZOOKEEPER-3913](https://issues.apache.org/jira/browse/ZOOKEEPER-3913) - Upgrade to Netty 4.1.50.Final
* [ZOOKEEPER-3919](https://issues.apache.org/jira/browse/ZOOKEEPER-3919) - Add ARM64 jobs to Travis-CI
* [ZOOKEEPER-3926](https://issues.apache.org/jira/browse/ZOOKEEPER-3926) - make the rc constant in the ClientCnxn
* [ZOOKEEPER-3934](https://issues.apache.org/jira/browse/ZOOKEEPER-3934) - upgrade dependency-check to version 6.0.0
* [ZOOKEEPER-3935](https://issues.apache.org/jira/browse/ZOOKEEPER-3935) - Handle float metrics in check_zookeeper
* [ZOOKEEPER-3941](https://issues.apache.org/jira/browse/ZOOKEEPER-3941) - Upgrade commons-cli to 1.4
* [ZOOKEEPER-3950](https://issues.apache.org/jira/browse/ZOOKEEPER-3950) - Add support for BCFKS key/trust store format
* [ZOOKEEPER-3952](https://issues.apache.org/jira/browse/ZOOKEEPER-3952) - Remove commons-lang from ZooKeeper
* [ZOOKEEPER-3956](https://issues.apache.org/jira/browse/ZOOKEEPER-3956) - Remove json-simple from ZooKeeper
* [ZOOKEEPER-3958](https://issues.apache.org/jira/browse/ZOOKEEPER-3958) - Update dependency versions and eliminate java docs warnings
* [ZOOKEEPER-3960](https://issues.apache.org/jira/browse/ZOOKEEPER-3960) - Update ZooKeeper client documentation about key file format parameters
* [ZOOKEEPER-3971](https://issues.apache.org/jira/browse/ZOOKEEPER-3971) - Auto close resources with try catch block
* [ZOOKEEPER-3978](https://issues.apache.org/jira/browse/ZOOKEEPER-3978) - Adding additional security metrics to zookeeper
* [ZOOKEEPER-3989](https://issues.apache.org/jira/browse/ZOOKEEPER-3989) - GenerateLoad needs to use log for protecting sensitive data
* [ZOOKEEPER-4000](https://issues.apache.org/jira/browse/ZOOKEEPER-4000) - use the computeIfAbsent to simplify the Leader#processSync method
* [ZOOKEEPER-4033](https://issues.apache.org/jira/browse/ZOOKEEPER-4033) - Remove unnecessary judgment of null
* [ZOOKEEPER-4048](https://issues.apache.org/jira/browse/ZOOKEEPER-4048) - Upgrade Mockito to 3.6.28 - allow builds on JDK16
* [ZOOKEEPER-4058](https://issues.apache.org/jira/browse/ZOOKEEPER-4058) - Update checkstyle-strict.xml by the latest version 8.39 of checkstyle
* [ZOOKEEPER-4188](https://issues.apache.org/jira/browse/ZOOKEEPER-4188) - add a doc about whoami CLI
* [ZOOKEEPER-4209](https://issues.apache.org/jira/browse/ZOOKEEPER-4209) - Update Netty version to 4.1.53.Final on 3.5 branch
* [ZOOKEEPER-4221](https://issues.apache.org/jira/browse/ZOOKEEPER-4221) - Improve the error message when message goes above jute.maxbufer size
* [ZOOKEEPER-4231](https://issues.apache.org/jira/browse/ZOOKEEPER-4231) - Add document for snapshot compression config

## Bug

* [ZOOKEEPER-1105](https://issues.apache.org/jira/browse/ZOOKEEPER-1105) - c client zookeeper_close not send CLOSE_OP request to server
* [ZOOKEEPER-1677](https://issues.apache.org/jira/browse/ZOOKEEPER-1677) - Misuse of INET_ADDRSTRLEN
* [ZOOKEEPER-1998](https://issues.apache.org/jira/browse/ZOOKEEPER-1998) - C library calls getaddrinfo unconditionally from zookeeper_interest
* [ZOOKEEPER-2164](https://issues.apache.org/jira/browse/ZOOKEEPER-2164) - fast leader election keeps failing
* [ZOOKEEPER-2307](https://issues.apache.org/jira/browse/ZOOKEEPER-2307) - ZooKeeper not starting because acceptedEpoch is less than the currentEpoch
* [ZOOKEEPER-2475](https://issues.apache.org/jira/browse/ZOOKEEPER-2475) - Include ZKClientConfig API in zoookeeper javadoc
* [ZOOKEEPER-2490](https://issues.apache.org/jira/browse/ZOOKEEPER-2490) - infinitely connect on windows
* [ZOOKEEPER-2836](https://issues.apache.org/jira/browse/ZOOKEEPER-2836) - QuorumCnxManager.Listener Thread Better handling of SocketTimeoutException
* [ZOOKEEPER-3112](https://issues.apache.org/jira/browse/ZOOKEEPER-3112) - fd leak due to UnresolvedAddressException on connect.
* [ZOOKEEPER-3215](https://issues.apache.org/jira/browse/ZOOKEEPER-3215) - Handle Java 9/11 additions of covariant return types to java.nio.ByteBuffer methods
* [ZOOKEEPER-3426](https://issues.apache.org/jira/browse/ZOOKEEPER-3426) - ZK prime_connection(the Handshake) can complete without reading all the payload.
* [ZOOKEEPER-3579](https://issues.apache.org/jira/browse/ZOOKEEPER-3579) - handle NPE gracefully when the watch parameter of zookeeper java client is null
* [ZOOKEEPER-3613](https://issues.apache.org/jira/browse/ZOOKEEPER-3613) - ZKConfig fails to return proper value on getBoolean() when user accidentally includes spaces at the end of the value
* [ZOOKEEPER-3642](https://issues.apache.org/jira/browse/ZOOKEEPER-3642) - Data inconsistency when the leader crashes right after sending SNAP sync
* [ZOOKEEPER-3644](https://issues.apache.org/jira/browse/ZOOKEEPER-3644) - Data loss after upgrading standalone ZK server 3.4.14 to 3.5.6 with snapshot.trust.empty=true
* [ZOOKEEPER-3651](https://issues.apache.org/jira/browse/ZOOKEEPER-3651) - NettyServerCnxnFactoryTest is flaky
* [ZOOKEEPER-3653](https://issues.apache.org/jira/browse/ZOOKEEPER-3653) - Audit Log feature fails in a stand alone zookeeper setup
* [ZOOKEEPER-3654](https://issues.apache.org/jira/browse/ZOOKEEPER-3654) - Incorrect *_CFLAGS handling in Automake
* [ZOOKEEPER-3656](https://issues.apache.org/jira/browse/ZOOKEEPER-3656) - SyncRequestProcessor doesn&#39;t update lastFlushTime correctly on observers
* [ZOOKEEPER-3667](https://issues.apache.org/jira/browse/ZOOKEEPER-3667) - set jute.maxbuffer hexadecimal number throw parseInt error
* [ZOOKEEPER-3698](https://issues.apache.org/jira/browse/ZOOKEEPER-3698) - NoRouteToHostException when starting large ZooKeeper cluster on localhost
* [ZOOKEEPER-3699](https://issues.apache.org/jira/browse/ZOOKEEPER-3699) - upgrade jackson-databind to address CVE-2019-20330
* [ZOOKEEPER-3701](https://issues.apache.org/jira/browse/ZOOKEEPER-3701) - Split brain on log disk full
* [ZOOKEEPER-3710](https://issues.apache.org/jira/browse/ZOOKEEPER-3710) - [trivial bug] fix compile error in PurgeTxnTest introduced by ZOOKEEPER-3231
* [ZOOKEEPER-3726](https://issues.apache.org/jira/browse/ZOOKEEPER-3726) - invalid ipv6 address comparison in C client
* [ZOOKEEPER-3737](https://issues.apache.org/jira/browse/ZOOKEEPER-3737) - Unable to eliminate log4j1 transitive dependency
* [ZOOKEEPER-3738](https://issues.apache.org/jira/browse/ZOOKEEPER-3738) - Avoid use of broken codehaus properties-maven-plugin
* [ZOOKEEPER-3739](https://issues.apache.org/jira/browse/ZOOKEEPER-3739) - Remove use of com.sun.nio.file.SensitivityWatchEventModifier
* [ZOOKEEPER-3745](https://issues.apache.org/jira/browse/ZOOKEEPER-3745) - Update copyright notices from 2019 to 2020
* [ZOOKEEPER-3748](https://issues.apache.org/jira/browse/ZOOKEEPER-3748) - Resolve release requirements in download page
* [ZOOKEEPER-3769](https://issues.apache.org/jira/browse/ZOOKEEPER-3769) - fast leader election does not end if leader is taken down
* [ZOOKEEPER-3772](https://issues.apache.org/jira/browse/ZOOKEEPER-3772) - JettyAdminServer should not allow HTTP TRACE method
* [ZOOKEEPER-3780](https://issues.apache.org/jira/browse/ZOOKEEPER-3780) - restore Version.getRevision() to be backward compatible
* [ZOOKEEPER-3781](https://issues.apache.org/jira/browse/ZOOKEEPER-3781) - Zookeeper 3.5.7 not creating snapshot
* [ZOOKEEPER-3782](https://issues.apache.org/jira/browse/ZOOKEEPER-3782) - Replace filter with list comprehension for returning list in zk-merge-pr.py
* [ZOOKEEPER-3793](https://issues.apache.org/jira/browse/ZOOKEEPER-3793) - Request throttling is broken when RequestThrottler is disabled or configured incorrectly.
* [ZOOKEEPER-3801](https://issues.apache.org/jira/browse/ZOOKEEPER-3801) - Fix Jenkins link in pom
* [ZOOKEEPER-3814](https://issues.apache.org/jira/browse/ZOOKEEPER-3814) - ZooKeeper config propagates even with disabled dynamic reconfig
* [ZOOKEEPER-3818](https://issues.apache.org/jira/browse/ZOOKEEPER-3818) - fix zkServer.sh status command to support SSL-only server
* [ZOOKEEPER-3829](https://issues.apache.org/jira/browse/ZOOKEEPER-3829) - Zookeeper refuses request after node expansion
* [ZOOKEEPER-3830](https://issues.apache.org/jira/browse/ZOOKEEPER-3830) - After add a new node, zookeeper cluster won&#39;t commit any proposal if this new node is leader
* [ZOOKEEPER-3832](https://issues.apache.org/jira/browse/ZOOKEEPER-3832) - ZKHostnameVerifier rejects valid certificates with subjectAltNames
* [ZOOKEEPER-3842](https://issues.apache.org/jira/browse/ZOOKEEPER-3842) - Rolling scale up of zookeeper cluster does not work with reconfigEnabled=false
* [ZOOKEEPER-3863](https://issues.apache.org/jira/browse/ZOOKEEPER-3863) - Do not track global sessions in ReadOnlyZooKeeperServer
* [ZOOKEEPER-3865](https://issues.apache.org/jira/browse/ZOOKEEPER-3865) - fix backward-compatibility for ZooKeeperServer constructor
* [ZOOKEEPER-3876](https://issues.apache.org/jira/browse/ZOOKEEPER-3876) - zkServer.sh status command fails when IPV6 is configured
* [ZOOKEEPER-3877](https://issues.apache.org/jira/browse/ZOOKEEPER-3877) - JMX Bean RemotePeerBean should enclose IPV6 host in square bracket same as LocalPeerBean
* [ZOOKEEPER-3878](https://issues.apache.org/jira/browse/ZOOKEEPER-3878) - Client connection fails if IPV6 is not enclosed in square brackets
* [ZOOKEEPER-3885](https://issues.apache.org/jira/browse/ZOOKEEPER-3885) - zoo_aremove_watches segfault: zk_hashtable needs locking!
* [ZOOKEEPER-3891](https://issues.apache.org/jira/browse/ZOOKEEPER-3891) - ZKCli commands give wrong error message &quot;Authentication is not valid&quot; for insufficient permissions
* [ZOOKEEPER-3895](https://issues.apache.org/jira/browse/ZOOKEEPER-3895) - Client side NullPointerException in case of empty Multi operation
* [ZOOKEEPER-3905](https://issues.apache.org/jira/browse/ZOOKEEPER-3905) - Race condition causes sessions to be created for clients even though their certificate authentication has failed
* [ZOOKEEPER-3911](https://issues.apache.org/jira/browse/ZOOKEEPER-3911) - Data inconsistency caused by DIFF sync uncommitted log
* [ZOOKEEPER-3933](https://issues.apache.org/jira/browse/ZOOKEEPER-3933) - owasp failing with json-simple-1.1.1.jar: CVE-2020-10663, CVE-2020-7712
* [ZOOKEEPER-3937](https://issues.apache.org/jira/browse/ZOOKEEPER-3937) - C client: avoid out-of-order packets during SASL negotiation
* [ZOOKEEPER-3943](https://issues.apache.org/jira/browse/ZOOKEEPER-3943) - Zookeeper Inspector throwing NullPointerExceptions and not displaying properly
* [ZOOKEEPER-3944](https://issues.apache.org/jira/browse/ZOOKEEPER-3944) - zookeeper c api sasl client memory leak
* [ZOOKEEPER-3951](https://issues.apache.org/jira/browse/ZOOKEEPER-3951) - Compile Error in Zookeeper.c without SASL
* [ZOOKEEPER-3954](https://issues.apache.org/jira/browse/ZOOKEEPER-3954) - use of uninitialized data in zookeeper-client/zookeeper-client-c/src/zookeeper.c:free_auth_completion
* [ZOOKEEPER-3955](https://issues.apache.org/jira/browse/ZOOKEEPER-3955) - added a shebang or a &#39;shell&#39; directive to lastRevision.sh
* [ZOOKEEPER-3979](https://issues.apache.org/jira/browse/ZOOKEEPER-3979) - Clients can corrupt the audit log
* [ZOOKEEPER-3983](https://issues.apache.org/jira/browse/ZOOKEEPER-3983) - C client test suite hangs forever &#39;sss&#39; is configured in /etc/nsswitch.conf
* [ZOOKEEPER-3987](https://issues.apache.org/jira/browse/ZOOKEEPER-3987) - Build failures when running surefire tests concurrently due to bind address already in use
* [ZOOKEEPER-3991](https://issues.apache.org/jira/browse/ZOOKEEPER-3991) - QuorumCnxManager Listener port bind retry does not retry DNS lookup
* [ZOOKEEPER-3992](https://issues.apache.org/jira/browse/ZOOKEEPER-3992) - addWatch api should check the null watch
* [ZOOKEEPER-3994](https://issues.apache.org/jira/browse/ZOOKEEPER-3994) - disconnect reason wrong
* [ZOOKEEPER-4045](https://issues.apache.org/jira/browse/ZOOKEEPER-4045) - CVE-2020-25649 - Upgrade jackson databind to 2.10.5.1
* [ZOOKEEPER-4050](https://issues.apache.org/jira/browse/ZOOKEEPER-4050) - Zookeeper Inspector reports &quot;List of default node viewers is empty&quot; when not specifically run from the zookeeper-contrib/zookeeper-contrib-zooinspector directory
* [ZOOKEEPER-4055](https://issues.apache.org/jira/browse/ZOOKEEPER-4055) - Dockerfile can&#39;t build Zookeeper C client library
* [ZOOKEEPER-4191](https://issues.apache.org/jira/browse/ZOOKEEPER-4191) - Missing executable bits in source release tarball
* [ZOOKEEPER-4199](https://issues.apache.org/jira/browse/ZOOKEEPER-4199) - Avoid thread leak in QuorumRequestPipelineTest
* [ZOOKEEPER-4200](https://issues.apache.org/jira/browse/ZOOKEEPER-4200) - WatcherCleanerTest often fails on macOS Catalina
* [ZOOKEEPER-4201](https://issues.apache.org/jira/browse/ZOOKEEPER-4201) - C client: SASL-related compilation issues on macOS Catalina
* [ZOOKEEPER-4205](https://issues.apache.org/jira/browse/ZOOKEEPER-4205) - Test fails when port 8080 is in use
* [ZOOKEEPER-4207](https://issues.apache.org/jira/browse/ZOOKEEPER-4207) - New CI pipeline checks out master in branch builds too
* [ZOOKEEPER-4219](https://issues.apache.org/jira/browse/ZOOKEEPER-4219) - Quota checks break setData in multi transactions
* [ZOOKEEPER-4220](https://issues.apache.org/jira/browse/ZOOKEEPER-4220) - Potential redundant connection attempts during leader election
* [ZOOKEEPER-4230](https://issues.apache.org/jira/browse/ZOOKEEPER-4230) - Use dynamic temp folder instead of static temp folder in RestMain
* [ZOOKEEPER-4232](https://issues.apache.org/jira/browse/ZOOKEEPER-4232) - InvalidSnapshotTest corrupts its own test data

## Test

* [ZOOKEEPER-3664](https://issues.apache.org/jira/browse/ZOOKEEPER-3664) - test

## Wish

* [ZOOKEEPER-3415](https://issues.apache.org/jira/browse/ZOOKEEPER-3415) - convert internal logic to use java 8 streams
* [ZOOKEEPER-3763](https://issues.apache.org/jira/browse/ZOOKEEPER-3763) - Restore ZKUtil.deleteRecursive in order to help compatibility of applications with 3.5 and 3.6

## Task

* [ZOOKEEPER-3669](https://issues.apache.org/jira/browse/ZOOKEEPER-3669) - Use switch Statement in ClientCnxn SendThread
* [ZOOKEEPER-3677](https://issues.apache.org/jira/browse/ZOOKEEPER-3677) - owasp checker failing for - CVE-2019-17571 Apache Log4j 1.2 deserialization of untrusted data in SocketServer
* [ZOOKEEPER-3695](https://issues.apache.org/jira/browse/ZOOKEEPER-3695) - Source release tarball does not match repository in 3.6.0
* [ZOOKEEPER-3696](https://issues.apache.org/jira/browse/ZOOKEEPER-3696) - Support alternative algorithms for ACL digest
* [ZOOKEEPER-3704](https://issues.apache.org/jira/browse/ZOOKEEPER-3704) - upgrade maven dependency-check to 5.3.0
* [ZOOKEEPER-3733](https://issues.apache.org/jira/browse/ZOOKEEPER-3733) - Fix issues reported in 3.6.0rc3
* [ZOOKEEPER-3734](https://issues.apache.org/jira/browse/ZOOKEEPER-3734) - upgrade jackson-databind to address CVE-2020-8840
* [ZOOKEEPER-3751](https://issues.apache.org/jira/browse/ZOOKEEPER-3751) - upgrade jackson-databind to 2.10 from 2.9
* [ZOOKEEPER-3794](https://issues.apache.org/jira/browse/ZOOKEEPER-3794) - upgrade netty to address CVE-2020-11612
* [ZOOKEEPER-3817](https://issues.apache.org/jira/browse/ZOOKEEPER-3817) - owasp failing due to CVE-2020-9488
* [ZOOKEEPER-3896](https://issues.apache.org/jira/browse/ZOOKEEPER-3896) - Migrate Jenkins jobs to ci-hadoop.apache.org
* [ZOOKEEPER-3957](https://issues.apache.org/jira/browse/ZOOKEEPER-3957) - Create Owasp check build on new Jenkins instance
* [ZOOKEEPER-3962](https://issues.apache.org/jira/browse/ZOOKEEPER-3962) - Create .asf.yaml file for ZooKeeper repo
* [ZOOKEEPER-3967](https://issues.apache.org/jira/browse/ZOOKEEPER-3967) - Jetty License Update
* [ZOOKEEPER-3973](https://issues.apache.org/jira/browse/ZOOKEEPER-3973) - Create configuration files GitHub Actions CI builds
* [ZOOKEEPER-3980](https://issues.apache.org/jira/browse/ZOOKEEPER-3980) - Fix Jenkinsfiles with new tool names
* [ZOOKEEPER-3981](https://issues.apache.org/jira/browse/ZOOKEEPER-3981) - Flaky test MultipleAddressTest::testGetValidAddressWithNotValid
* [ZOOKEEPER-4017](https://issues.apache.org/jira/browse/ZOOKEEPER-4017) - Owasp check failing - Jetty 9.4.32 - CVE-2020-27216
* [ZOOKEEPER-4023](https://issues.apache.org/jira/browse/ZOOKEEPER-4023) - dependency-check:check failing - Jetty 9.4.34.v20201102 - CVE-2020-27218
* [ZOOKEEPER-4056](https://issues.apache.org/jira/browse/ZOOKEEPER-4056) - Update copyright notices from 2020 to 2021
* [ZOOKEEPER-4233](https://issues.apache.org/jira/browse/ZOOKEEPER-4233) - dependency-check:check failing - Jetty 9.4.35.v20201120 - CVE-2020-27223

## Sub-task

* [ZOOKEEPER-837](https://issues.apache.org/jira/browse/ZOOKEEPER-837) - cyclic dependency ClientCnxn, ZooKeeper
* [ZOOKEEPER-3574](https://issues.apache.org/jira/browse/ZOOKEEPER-3574) - Close quorum socket asynchronously to avoid server shutdown stalled by long socket closing time
* [ZOOKEEPER-3575](https://issues.apache.org/jira/browse/ZOOKEEPER-3575) - Moving sending packets in Learner to a separate thread
* [ZOOKEEPER-3845](https://issues.apache.org/jira/browse/ZOOKEEPER-3845) - Add metric JVM_PAUSE_TIME
* [ZOOKEEPER-3852](https://issues.apache.org/jira/browse/ZOOKEEPER-3852) - Upgrade jUnit in ZooKeeper-Jute
* [ZOOKEEPER-3854](https://issues.apache.org/jira/browse/ZOOKEEPER-3854) - Upgrade jUnit in ZooKeeper-Recipes
* [ZOOKEEPER-3855](https://issues.apache.org/jira/browse/ZOOKEEPER-3855) - Upgrade jUnit in ZooKeeper-Metrics-providers
* [ZOOKEEPER-3856](https://issues.apache.org/jira/browse/ZOOKEEPER-3856) - Add a couple metrics to track inflight diff syncs and snap syncs
* [ZOOKEEPER-3859](https://issues.apache.org/jira/browse/ZOOKEEPER-3859) - Add a couple request processor metrics
* [ZOOKEEPER-3862](https://issues.apache.org/jira/browse/ZOOKEEPER-3862) - Re-enable deprecation check after finishing jUnit upgrade
* [ZOOKEEPER-3872](https://issues.apache.org/jira/browse/ZOOKEEPER-3872) - Upgrade jUnit in ZooKeeper-server
* [ZOOKEEPER-3953](https://issues.apache.org/jira/browse/ZOOKEEPER-3953) - Update hamcrest-library to version 2.2
