it is a subtask of #5139.

All is required is to create UT GeneratedJavadocTokenTypesTest that works the same way as https://github.com/checkstyle/checkstyle/blob/master/src/test/java/com/puppycrawl/tools/checkstyle/grammars/GeneratedJavaTokenTypesTest.java but for javadoc tokens - https://github.com/checkstyle/checkstyle/blob/master/src/main/java/com/puppycrawl/tools/checkstyle/api/JavadocTokenTypes.java

values of JavadocTokenTypes should never change.