NIFI-8974 Integrate KerberosUserService with HDFS processors
NIFI-8980 Integrate KerberosUserService with Kafka 2.6 processors
- Introduced SelfContainerKerberosUserService to restrict which impls can be used with Kafka
- Add variations of KerberosUser doAs that allow setting the context ClassLoader
- Add additional unit tests for configurations
This closes#5277
Signed-off-by: David Handermann <exceptionfactory@apache.org>