Make client to be Java 11 compatible

[Shaddoll]

what?

Make client to be Java 11 compatible. Use Java 11 to compile Java 8 code and release Java 8 bytecode to prepare for future migartion.

[coveralls]

Pull Request Test Coverage Report for Build 671

• 6 of 6 (100.0%) changed or added relevant lines in 2 files are covered.
• 2 unchanged lines in 2 files lost coverage.
• Overall coverage decreased (-0.003%) to 71.838%

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Files with Coverage Reduction	New Missed Lines	%
src/main/java/com/uber/cadence/internal/sync/DeterministicRunnerImpl.java	1	84.1%
src/main/java/com/uber/cadence/internal/worker/BlockCallerPolicy.java	1	62.5%

Totals
Change from base Build 661:	-0.003%
Covered Lines:	10678
Relevant Lines:	14864

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💛 - Coveralls