Maven Enforcer Plugin provides goals to control certain environmental constraints such as Maven version, JDK version and OS family along with many more standard rules and user created rules.
char-set-encoding-rule is a user created custom rule to force the character set of any or all the files in the build.
It often happens that when files go around between different members of a programming team – especially if the team is international – they also change their character encoding by accident. This Maven plugin check that all the files (or only selected files) are encoded in the proper encoding. In this time and age (year 2016) that would most likely be UTF-8 encoding but other encodings are also still used, often with good reason in strictly localized environments.
The rule uses the icu4j libraries to try to deduct the file’s character set. Unfortunately, it is not always possible to get a 100% exact result. There is always some guessing involved, especially when the file contains no text or no text with 8-bit characters. Therefore, char-set-encoding-rule does not actually try to deduct what a file’s character set is. Instead, it asks from icu4j if that file’s char set is compatible with the wanted character set.