* Refactor execute around the idiom

* fix checkstyle errors
Co-authored-by: NSubhrodip Mohanta <hello@subho.xyz>

* Moves eip-aggregator to Java 11

* Moves eip-message-channel to Java 11

* Moves eip-publish-subscribe to Java 11

* Moves eip-splitter to Java 11

* Moves eip-wire-tap to Java 11

* Moves event-aggregator to Java 11

* Moves event-asynchronous to Java 11

* Moves event-driven-architecture to Java 11

* Moves event-queue to Java 11

* Moves event-sourcing to Java 11

* Moves execute-around to Java 11

* Moves extension-objects to Java 11

* Reduces checkstyle errors in execute-around

* Reduces checkstyle errors in extension-objects

* Add custom license header style in order to comply with Google's Checkstyle format

* Update license headers to comply with Google's Checkstyle format

Replace try statements that close a resource in the finally block with a
try-with-resources statement [1].

This commit was created automatically by Diffblue refactorings (https://www.diffblue.com/).

[1] https://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html

Adjust checkstyle rules. Make checkstyle fail the build when violations are found. Correct all current checkstyle violations.