Added core interfaces for property support.
Added MemProperty
no-op property verifier and publisher.
Added NotNullVerifier
Added some convenience methods to PropertyFactory.
Added TypeCheckerVerifier
Added ConstSource
Added DelegatedPropertySource
Added CombinedVerifier
Added ListVerifier
Introducing: SimpleListenerRegistry
Added ProxyListenerRegistry.
Backward incompatible change: ListenerManager no longer has a generic argument for the argument type because it is an unnecessary overhead.
Added ProxyListenerRegistry.onEvent
Added DefaultPropertySourceProxy
Documented: PropertySource
Documented: MutableProperty
Documented: PropertyPublisher
Documented: PropertyVerifier
Documented: MutablePropertyProxy