* skip travis on doc only changes

* more selective ignoring of examples folder

* CompactionTask: Reject empty intervals on construction.

They don't make sense anyway, and it's better to fail fast.

* Switch API.

Fixes #6063.

Class org.apache.hadoop.conf.Configuration inside extensions should be used with caution.
By default, the configuration uses the context class loader of the current thread set to the
class loader used to load the application. Because of isolation between the application and
extensions we must explicitely set the class loader to extension class loader to be able
load classes specified in hadoop configuration file.

* Various changes about druid-services module

* Patch improvements from reviewer

* Add ToArrayCallWithZeroLengthArrayArgument & ArraysAsListWithZeroOrOneArgument into inspection profile

* Fix ArraysAsListWithZeroOrOneArgument

* Fix conflict

* Fix ToArrayCallWithZeroLengthArrayArgument

* Fix AliEqualsAvoidNull

* Remove blank line

* Remove unused import clauses

* Fix code style in TopNQueryRunnerTest

* Fix conflict

* Don't use Collections.singletonList when converting the type of array type

* Add argLine into maven-surefire-plugin in druid-process module & increase the timeout value for testMoveSegment testcase

* Roll back the latest commit

* Add java.io.File#toURL() into druid-forbidden-apis

* Using Boolean.parseBoolean instead of Boolean.valueOf for CliCoordinator#isOverlord

* Add a new regexp element into stylecode xml file

* Fix style error for new regexp

* Set the level of ArraysAsListWithZeroOrOneArgument as WARNING

* Fix style error for new regexp

* Add option BY_LEVEL for ToArrayCallWithZeroLengthArrayArgument in inspection profile

* Roll back the level as ToArrayCallWithZeroLengthArrayArgument as ERROR

* Add toArray(new Object[0]) regexp into checkstyle config file & fix them

* Set the level of ArraysAsListWithZeroOrOneArgument as ERROR & Roll back the level of ToArrayCallWithZeroLengthArrayArgument as WARNING until Youtrack fix it

* Add a comment for string equals regexp in checkstyle config

* Fix code format

* Add RedundantTypeArguments as ERROR level inspection

* Fix cannot resolve symbol datasource

See issue #6030

* Remove the unsafe loop from the benchmark

* Removing unused variables

Similar issue to https://github.com/apache/incubator-druid/issues/6028.

Synchronize scheduled poll() calls in SQLMetadataRuleManager to prevent flakiness in SqlMetadataRuleManagerTest (#6033)

Check the kafka topic when compacring checkpoints from tasks and the one stored in metastore (#6015)

* Add support to filter on datasource for active tasks

* Added datasource filter to sql query for active tasks
* Fixed unit tests

* Address PR comments

* SQL: Add server-wide default time zone config.

* Switch API.

* update readme

* add disclaimer

* Fix NPE while handling CheckpointNotice

* fix code style

* Fix test

* fix test

* add a log for creating a new taskGroup

* fix backward compatibility in KafkaIOConfig

* this will fix it

* filter destinations to not consider servers already serving segment

* fix it

* cleanup

* fix opposite day in ImmutableDruidServer.equals

* simplify

* show that flatten will also work with avro extension

* fix url

* fix explosion in curator load queue peon caused by additional logging, as well as annoying chatty log

* remove log message

* Update license headers.

For compliance with http://www.apache.org/legal/src-headers.html.

* More license adjustments.

* Fix mistakenly edited package line.

False failures on Travis due to spurious timeout (in turn due to noisy
neighbors) is a bigger problem than legitimate failures taking too long
to time out. So it makes sense to extend timeouts.

* Support limit for timeseries query (#5894)

* Fix tests

* Address PR comments

* Try to fix teamcity inspection checks

* Remove unused method from VirtualColumns

* Remove unused import statement

* add config values for GCS deep storage

* fix config values for GCS deep storage

- Setting druid.request.logging.delegate has no effect. 
- The provider is injected based on a type parameter & this looks to be scoped to delegate for filtered loggers

They are bad because datasources are used as paths on filesystems,
and slashes invariably make things get stored improperly.

change default compaction task target size from 800MB to 400MB to fall within range of what docs recommend for segment sizing (#5930)

* Prevent KafkaSupervisor NPE in checkPendingCompletionTasks (#5900)

* throw IAE in generateSequenceName if groupId not found in taskGroups
* add null check in checkPendingCompletionTasks

* Add warn log in checkPendingCompletionTasks

* Address PR comments

Replace warn with error log

* Address PR comments

* change signature of generateSequenceName to take a TaskGroup object instead of int

* Address comments

* Remove unnecessary method from KafkaSupervisorTest

* more coordinator logging to help give context to load queue peon log messages

* fix style

* more chill load queue peon log messages