# ReleaseFlag.java calls String.equalsFoldCase, which is new in Java 26. The compiler is JDK 27's javac both times.

$ javac --release 25 ReleaseFlag.java
    <repo>/lanes/src/ReleaseFlag.java:8: error: cannot find symbol
            System.out.println("ABC".equalsFoldCase("abc"));
                                    ^
      symbol:   method equalsFoldCase(String)
      location: class String
    1 error
    exit=1

$ javac -source 25 -target 25 ReleaseFlag.java
    warning: [options] location of system modules is not set in conjunction with -source 25
      not setting the location of system modules may lead to class files that cannot run on JDK 25
        --release 25 is recommended instead of -source 25 -target 25 because it sets the location of system modules automatically
    1 warning
    exit=0

$ java -cp rf-b ReleaseFlag      (JDK 25)
    Exception in thread "main" java.lang.NoSuchMethodError: 'boolean java.lang.String.equalsFoldCase(java.lang.String)'
    	at ReleaseFlag.main(ReleaseFlag.java:8)

$ java -cp rf-b ReleaseFlag      (JDK 27)
    true