In the following output, constant pool entry #34 is both unused and a duplicate (of #2). This is not uncommon, at least in the javadoc classes in the same package. This should be fixed.

$ /opt/jdk/1.7.0/bin/javap -v build/classes/com/sun/tools/javadoc/SourcePositionImpl.class | grep java/io/File
const #2 = class #47; // java/io/File
const #3 = Method #2.#48; // java/io/File."<init>":(Ljava/lang/String;)V
const #30 = Asciz ()Ljava/io/File;;
const #34 = class #47; // java/io/File
const #47 = Asciz java/io/File;
   11: new #2; //class java/io/File
   19: invokespecial #3; //Method java/io/File."<init>":(Ljava/lang/String;)V
     stack = [ class java/io/File ]