This closes #5054.

This closes #5051.

This closes #5020.

This closes #5042.

This closes #5012.

Update to the latest checkstyle version and fix the errors not
previously detected.

This closes #5044.

This closes #5029

This closes #5041

This closes #5027.

This closes #5015.

This closes #5039.

Before, the "hadoop2" profile would create a binary release for whatever
happens to be the default hadoop.version.

This closes #5033.

This close #4794.

This commit changes the serialization of the ParameterTool such that only the
data map is contained. The defaultData and the unrequestedParameters maps are
not serialized because they are only used on the client side. Additionally, the
defaultData and unrequestedParameters map are being made thread safe by using
ConcurrentHashMaps.

This closes #4921.

This closes #8110.

ProducerFencedException can happen if we restore twice from the same checkpoint
or if we restore from an old savepoint. In both cases transactional.ids that we
want to recoverAndCommit have been already committed and reused. Reusing mean
that they will be known by Kafka's brokers under newer producerId/epochId,
which will result in ProducerFencedException if we try to commit again some
old (and already committed) transaction.

Ignoring this exception might hide some bugs/issues, because instead of failing
we might have a semi silent (with a warning) data loss.

This closes #4883.

This closes #5026.

This closes #5025.

This closes #4950.

+ includes a new unit tests for recursive uploads to hfds:// targets
+ add a unit test for recursive file uploads to s3:// via s3a

[FLINK-4228][yarn/s3] turn the dependencies around

Instead of having flink-s3-fs-hadoop depend on flink-yarn_<scala_version>,
let flink-yarn depend on the s3 filesystem and implement the test there.
This is safer with regards to the scala-independent flink-s3-fs-hadoop project.

[FLINK-4228][yarn] change the S3 upload tests to use Hadoop's S3 implementations

This is how YARN would use it and what should really be tested.

[FLINK-4228][yarn] enable S3 tests for newer Hadoop versions

- requires the 'include_hadoop_aws' build profile (or property) to be set
- requires a newer aws-sdk version (than Hadoop pulls in) to work with our
  httpcomponents version
- we also add a check that at least one S3 implementation is tested to not
silently ignore all tests because of such a missing dependency

This closes #4939.

This closes #4397