- Remove redundant uses of WrapperMock
- Use assertThat() from JUnit, not hamcrest
- Use hamcrest Matchers everywhere (not BaseMatchers etc.)
- Favor Mockito's argThat() over using ArgumentCaptor (more succinct)
- Delete useless test classes
- Change interface to use (CommandSender, List<String> arguments)
- Use CommandArgumentDescription#name instead of "label" (to prevent confusion between command labels and arguments)
- Simplify command difference computation in CommandHandler (no longer consider argument difference)
Replaced many classes to use Wrapper to get singletons and replaced the test setups to use the WrapperMock instead of setting fields through reflection