Ports the CurrentJobsOverviewHandler to the new REST endpoint by letting it implement
the LegacyRestHandler interface. This commit changes the JobDetails JSON such that it
now contains the number of tasks for each ExecutionState, including SCHEDULED,
DEPLOYING, CREATED and RECONCILING. These state will now also be displayed in the
web frontend.

Change MultipleJobsDetails to store a Collection<JobDetails> instead of JobDetails[]

Use MultipleJobsDetails#FIELD_NAME_ for serialization in CurrentJobsOverviewHandler

This closes #4688.

This is not complete refactor, some methods still relay on the order of the
new and old operators.

[FLINK-7619] Improved abstraction of AbstractAsyncIOCallable to better fit the current usage pattern.

Recently, the aligned window operators were removes, these classes where
leftover after that removal.

[FLINK-7656] [runtime] Switch to user classloader before calling initializeOnMaster and finalizeOnMaster.

This closes #4690.

This closes #4685.

The updateCredentials delay is an ignorable warning that occurs due to
the fact that the default credential update delay is longer than the
await termination timeout when shutting down KPL.

See https://github.com/awslabs/amazon-kinesis-producer/issues/10 for
details.

This closes #4657.

KinesisProducerLibrary (KPL) 0.10.x had been using a
One-New-Thread-Per-Request model for all requests sent to AWS Kinesis,
which is very expensive.

0.12.4 introduced a new ThreadingMode - Pooled, which will use a thread
pool. This hugely improves KPL's performance and reduces consumed
resources. By default, KPL still uses per-request mode. We should
explicitly switch FlinkKinesisProducer's KPL threading mode to 'Pooled'.

This closes #4656.

This commit changes the fencing behaviour such that a component which is not the
leader will set its fencing token to null. This distinction allows to throw different
exceptions depending on whether it is a token mismatch or whether the receiver has
no fencing token set (== not being the leader).

This closes #4689.

This also adds an end-to-end test that verifies correct order for both
classes and resources.

This closes #4635.

This closes #4692.

Similar to a registration error we should also delay the retrying registration in case of
connection error which could happen if the remote endpoint has not been started yet.

This closes #4686.

Lets DashboardConfigHandler implement the LegacyRestHandler. Moreover, this
commit defines the appropriate DashboardConfigurationHeaders.

The DispatcherRestEndpoint registers the DashboardConfigHandler.

This closes #4604.

Introduce LegacyRestHandler interface which the old REST handler have to implement
in order to make them usable for the RestServerEndpoint in combination with the
LegacyRestHandlerAdapter. The LegacyRestHandlerAdapter extends the AbstractRestHandler
and runs the LegacyRestHandler implementation.

As an example, this commit ports the ClusterOverviewHandler to the new interface. The
Dispatcher side still has to be properly implemented.

This closes #4603.

Adds the StaticFileContentHandler to the DispatcherRestEndpoint if the
flink-runtime-web dependency is in the classpath. In order to setup the
respective channel handler, this commit introduces the setupChannelHandlers
method to the RestServerEndpoint.

Refactor RestServerEndpoint#initializeHandler to support StaticFileServerHandler registration

This closes #4601.

This closes #3829.

This closes #4521.

This closes #4630.

Move metrics handlers under o.a.f.runtime.webmonitor.handlers

Move StaticFileServerHandler under o.a.f.runtime.webmonitor.files

This closes #4600.

With this change, the complete REST address (protocol://hostname:port) is retrieved
from the RestfulGateway. That way we decouple the RestHandlers from the underlying
RestServerEndpoint/WebRuntimeMonitor because they no longer have to know whether
HTTPs is enabled or not.

This closes #4599.

This commit creates the DispatcherRestEndpoint and integrates it with the
Dispatcher. The DispatcherRestEndpoint is created in the SessionClusterEntrypoint
and its address is passed to the Dispatcher such that it can answer the
requestRestAddress RPC.

This closes #4598.

By letting the AbstractRestHandler extend the RedirectHandler, we add redirection
capabilities to the AbstractRestHandler.

This closes #4597.

This closes #4662.

This closes #4677.

This closes #4663.

This fixes the netty check and makes all of them more robust against failures of
the executed commands counting the number of dependencies.

This closes #4653.

This closes #4646.

This closes #4644.