Support Calling Java Function in Python Executor and ModelBroadcast in Python (#2284)
Support Calling Java Function in Python Executor and ModelBroadcast in Python (#2284)

* support call java function in executor

* fix test

* fix style

* address comments

* add parallelism

* address comments

* fix partition num

* address comments

* fix typo

* fix typo

* add integration test

* address comments

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