The DeclarativeSlotPool.registerNewSlotsListener can be used to register a
DeclarativeSlotPool.NewSlotsListener which is notified whenever the
DeclarativeSlotPool receives new slots or reserved slots are freed.

This closes #14482.

This closes #14518.

It was not possible to just run 'mvn spotless:check', but instead one needed to use the fully qualified name of the plugin, i.e., 'mvn com.diffplug.spotless:spotless-maven-plugin:check'.

This is due to 'force-shading'; this module is declared as a child of the flink-parent pom (i.e., the root pom of the project), but is not actually declaring that very module as it's parent.
This seems to throw of maven, which fails to retrieve the plugin information from the parent.

Note that this is just a band-aid; a proper fix would declare flink-parent as the parent of force-shading, but this is the easier fix.

[FLINK-17331][runtime] Explicitly get the ByteBuf length of all classes which is written to NettyMessage

Currently, the length of some header fields in NettyMessage is hardcoded: InputChannelID, ExecutionAttemptID, e.t.c.
So if we make some changes for such field, then we are not ware that it also needs to change the respective length for related netty messages component.
This PR explicitly get the ByteBuf length of all classes which is written to NettyMessage to avoid such problems.

Display more informative message stating that Watermarks are only available when using
event time if there are no watermarks to display in the web UI.

This closes #14483.

This closes #14514.

This file can be used via:

$ git config blame.ignoreRevsFile .git-blame-ignore-revs

The reformatting increases file length for some files.

Keeping them inline does not work with google-java-format.

[FLINK-20756][python] Fix the bug that it doesn't support field access of expression containing Python UDF in the condition of Calc

This closes #14492.

This closes #14362
Co-authored-by: Nzhao.zhang <zhao.zhang@upai.com>

[FLINK-20620][table-planner-blink][python] Port BatchExecPythonCalc and StreamExecPythonCalc to Java

This closes #14496.

[FLINK-20712][python] Support join_lateral/left_outer_join_lateral to accept table function directly

This closes #14500.

[FLINK-20657][connectors/jdbc] Migrate jdbc InputFormat/LookupFunction to SimpleJdbcConnectionProvider for connection establishment

This closes #14466

This closes #13800

[FLINK-20736][table-planner-blink] Introduce StreamPhysicalRank & StreamPhysicalLimit, and make StreamExecRank & StreamExeLimit only extended from ExecNode

This closes #14472

[FLINK-20736][table-planner-blink] Introduce BatchPhysicalLimit, and make BatchExecLimit only extended from ExecNode

This closes #14472

[FLINK-20706][table-planner-blink] Introduce BatchPhysicalUnion, and make BatchExecUnion only extended from ExecNode

This closes #14455

[FLINK-20706][table-planner-blink] Introduce StreamPhysicalUnion, and make StreamExecUnion only extended from ExecNode

This closes #14455

This closes #14473.

This closes #14489

This closes #14447

This closes #14487.

This closes #14452

This closes #14387