Prevent NIO threads to execute and/or invoke any operation.
Add test for issue #2980

(cherry picked from commit b0586af65661cd2dbb35d938c1b1e1c75f718ae5)
Improved EventService, made executeEventCallback() method part of SPI.
Call connection listeners as event callback instead of calling them directly on IO thread.
Test fix.

(cherry picked from commit c3c48619c5274bd0635260581fea9ea38b744769)
Merge pull request #2993 from mdogan/fix/3.2/tcp-nio

Fixes operation execution/invocation on IO threads issue