Fix the checks in CheckMethodAdapter.checkIdentifier for V1_5 or more classes
Fix the checks in CheckMethodAdapter.checkIdentifier for V1_5 or more classes, and update all the callers. The requirements were changed in the specification of Java 5 (see section 4.3.2 of https://jcp.org/aboutJava/communityprocess/maintenance/jsr924/index.html).
Closes #317817 (closed)