[FLINK-14068][core] Final fixes #783

Job	Run time
Pre-compile Checks / Basic QA	8m 52s
Default (Java 8) / Compile	45m 37s
Default (Java 8) / Test (module: core)	35m 30s
Default (Java 8) / Test packaging/licensing	7m 7s
Default (Java 8) / Test (module: python)	14m 4s
Default (Java 8) / Test (module: table)	38m 34s
Default (Java 8) / E2E (group 1)	2h 13m 55s
Default (Java 8) / Test (module: connect)	21m 24s
Default (Java 8) / E2E (group 2)	1h 32m 27s
Default (Java 8) / Test (module: tests)	49m 20s
Default (Java 8) / Test (module: misc)	40m 43s
	8h 7m 33s

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