[HUDI-2167] HoodieCompactionConfig get HoodieCleaningPolicy NullPointerException

[tsianglei]

What is the purpose of the pull request

HUDI-2167
Fix org.apache.hudi.util.StreamerUtil#getHoodieClientConfig does not set HoodieCleaningPolicy but org.apache.hudi.config.HoodieCompactionConfig.Builder#build check the policy. Then will got NullPointerException.
Exception stack is:

Caused by: java.lang.NullPointerException: Name is null
	at java.lang.Enum.valueOf(Enum.java:236) ~[?:1.8.0_221]
	at org.apache.hudi.common.model.HoodieCleaningPolicy.valueOf(HoodieCleaningPolicy.java:24) ~[hudi-flink-bundle_2.11-0.9.0-SNAPSHOT.jar:0.9.0-SNAPSHOT]
	at org.apache.hudi.config.HoodieCompactionConfig$Builder.build(HoodieCompactionConfig.java:392) ~[hudi-flink-bundle_2.11-0.9.0-SNAPSHOT.jar:0.9.0-SNAPSHOT]
	at org.apache.hudi.util.StreamerUtil.getHoodieClientConfig(StreamerUtil.java:162) ~[hudi-flink-bundle_2.11-0.9.0-SNAPSHOT.jar:0.9.0-SNAPSHOT]
	at org.apache.hudi.util.StreamerUtil.createWriteClient(StreamerUtil.java:305) ~[hudi-flink-bundle_2.11-0.9.0-SNAPSHOT.jar:0.9.0-SNAPSHOT]
	at org.apache.hudi.sink.StreamWriteOperatorCoordinator.start(StreamWriteOperatorCoordinator.java:153) ~[hudi-flink-bundle_2.11-0.9.0-SNAPSHOT.jar:0.9.0-SNAPSHOT]
	at org.apache.flink.runtime.operators.coordination.OperatorCoordinatorHolder.start(OperatorCoordinatorHolder.java:189) ~[flink-dist_2.11-1.12.2.jar:1.12.2]
	at org.apache.flink.runtime.scheduler.SchedulerBase.startAllOperatorCoordinators(SchedulerBase.java:1253) ~[flink-dist_2.11-1.12.2.jar:1.12.2]
	at org.apache.flink.runtime.scheduler.SchedulerBase.startScheduling(SchedulerBase.java:624) ~[flink-dist_2.11-1.12.2.jar:1.12.2]
	at org.apache.flink.runtime.jobmaster.JobMaster.startScheduling(JobMaster.java:1032) ~[flink-dist_2.11-1.12.2.jar:1.12.2]
	at java.util.concurrent.CompletableFuture.uniRun(CompletableFuture.java:705) ~[?:1.8.0_221]

Brief change log

• add HoodieCleaningPolicy

Verify this pull request

(Please pick either of the following options)

This pull request is a trivial rework / code cleanup without any test coverage.

(or)

This pull request is already covered by existing tests, such as (please describe tests).

(or)

This change added tests and can be verified as follows:

(example:)

• Added integration tests for end-to-end.
• Added HoodieClientWriteTest to verify the change.
• Manually verified the change by running a job locally.

Committer checklist

• Has a corresponding JIRA in PR title & commit

• Commit message is descriptive of the change

• CI is green

• Necessary doc changes done or have another open PR

• For large changes, please consider breaking it into sub-tasks under an umbrella JIRA.

[hudi-bot]

CI report:

• 40aa431 Azure: SUCCESS

Bot commands

@hudi-bot supports the following commands:

• @hudi-bot run travis re-run the last Travis build
• @hudi-bot run azure re-run the last Azure build

[danny0405]

Isn't HoodieCleaningPolicy.KEEP_LATEST_COMMITS the default value ?

[tsianglei]

build() method get policy use compactionConfig.getString(CLEANER_POLICY_PROP),this method doesn't return default value, but null. if not set then will return null.

[danny0405]

The HoodieCompactionConfig would setDefaults first before build.

[danny0405]

Not a valid fix, close it.