[Java] remove threetenbp dependency

Created by: hugo-ma-alves

Hello

On this PR i removed the threetenbp dependency from java code base. I saw this change suggested on the issue #3258 Now by default the generated clients use java8 dates.

This change affected a lot of files, so it is big PR for review, fortunately most of the changes are on the samples.

Feedback appreciated, Thanks 😃

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