JavaPropFile is a Gradle Plugin with which you can...

Load properties files into Gradle Projects, Extension objects, other
Gradle objects.  Many object types supported.

Expand ${references} in Strings, text files, property values, recursively.
Variables to be referenced may be Gradle properties, extension objects,
other objects, user-supplied map, and all types.  Works with most object
types, using toString().

Documentation is at http://admc.com/projectdocs/gradle-javaPropFile-plugin/readme.html