* remove spring dep
move junit, logging, mockito under dep mgmt
* upgrade anti-corruption-layer deps
* async method invocation
* balking, bloc
* bridge to bytecode
* caching
* callback - cqrs
* component - health check
* hexagonal - metadata mapping
* rest of the patterns
* remove checkstyle, take spotless into use
* Add custom license header style in order to comply with Google's Checkstyle format
* Update license headers to comply with Google's Checkstyle format
* Fix issue #761: ThreadSafeDoubleCheckLocking.java: Instantiating by Reflection call will be successful if you do that firstly
* Create leader election module
* Create Interface of Instance and MessageManager
* Create implementations with token ring algorithm
* Change package structure.
Create basic message system.
* Implement heartbeat and heartbeat invoking message system
* Implement election message handler
* Add leader message handler
* Add main entry point
* Add comments
* Update README.md
* Fix checkstyle issue
* Add Unit Tests
* Add Unit Tests
* Add bully leader selection
* Change System.out to log print.
Add MIT license in each file.
* Add More java doc comments
* Add unit test
* Add unit tests
* Add subclass-sandbox
* Add Unit Test
* Add Unit Test
* Fix Typo
* Move dependency into parent pom.xml
* Change local valuable reference to be var