property-providers 
property-providers is a lightweight library for providing
java.util.Properties for your projects. At its heart there is the
FileWatchingPropertyProvider, which uses java.nio.file.WatchService to
detect changes in a property file and reloads the property file once a change is
detected. A PropertiesUpdateListener can be registered to be informed of
update events.
Maven
The library is available on Maven Central.
JavaDoc
License
MIT License