for this source:

class Test {
   String foo() {
       final String hello = "Hello!";
       return hello;
   }
}

javac generates this code, we are actually interested in the code for method foo():

java.lang.String foo();
    descriptor: ()Ljava/lang/String;
    flags: (0x0000)
    Code:
      stack=1, locals=2, args_size=1
         0: ldc #2 // String Hello!
         2: areturn
      LineNumberTable:
        line 4: 0

the max number of locals is set to 2 when actually there is no local used / needed

this issue was initially reported by Remi at amber-dev: http://mail.openjdk.java.net/pipermail/amber-dev/2018-September/003407.html