Fix sonars in server-pool

Fix sonars in server-pool

Addressed the following sonars in feature-server-pool:
- re-interrupt after catching an InterruptException
- reduce cognitive complexity
- cognitive complexity
- not enough arguments for logger message
- use UnaryOperator instead of Function
- update static fields via static methods
- too many break/continue in for-loop

Also fixed some Eclipse warnings:
- add parameter to generic types
- useless assignments
- newInstance() has been deprecated
- close streams

Issue-ID: POLICY-2616
Change-Id: Ibf6c20e6c2a7eb8c60e1b38f388d86a0f9b8804b
Signed-off-by: Jim Hahn <jrh3@att.com>