RealmAware client change for rest cache - support recursive persist listener

[xyuanlu]

Issues

• My PR addresses the following Helix issues and references them in the PR description:

#2659

Description

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This change adds support for recursive persist listener in realmAware ZkClient. As rest client cache will use recursive persist listener for ZK change events.

Tests

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  TestFederatedZkClient.testFederatedZkClientWithPersistListener

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Changes that Break Backward Compatibility (Optional)

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Documentation (Optional)

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Commits

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  1. Subject is separated from body by a blank line
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  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"

Code Quality

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[junkaixue]

Is this still a valid change?