Property files for localization requires to be encoded in ISO-8859-1. It results difficulties in reviewing localizing pull requires such as https://github.com/jenkinsci/maven-plugin/pull/86. It would be nice if property files in source directories can be written in UTF-8 letters.
There are two approaches:
Encode property files when compiling.
maven-resources-plugin copies files in the resources directory into the target directory. It doesn't provide a feature to encode property files.
Though native2ascii-maven-plugin encodes property files, it is provided only as beta for long time.
This might mean encoding property files in compilation time isn't a standard approach.
maven-antrun-plugin can run native2ascii (But it feels strange approach to me).
This approach would cause problems when testing plugins with "mvn hpi:run".
As property files aren't compiled and read from source directories directly at that time.
Make libraries reading property files accept UTF-8 letters.
I found existing property files are not encoded in ASCII, but ISO-8859-1. See more details in https://github.com/stapler/stapler/pull/105. ISO-8859-1 and UTF-8 are not compatible, and it looks difficult to detect decoding errors in Java.