After a terminology update in JavaSE 16, the JLS uses the phrase "enum classes" rather than "enum types": compare
https://docs.oracle.com/javase/specs/jls/se15/html/jls-8.html#jls-8.9
https://docs.oracle.com/javase/specs/jls/se17/html/jls-8.html#jls-8.9
The messages in javac's compiler properties should be aligned with the revised wording.
See "Consistent Class and Interface Terminology" document:
https://download.java.net/java/early_access/jdk16/docs/specs/class-terminology-jls.html
for the full terminology update.