com.sun.tools.classfile is a legacy proprietary class file processing library once used by some JDK command line tools like jdeps, jdeprscan, and javap. These tools have now all migrated to the ClassFile API, which provides better error handling and forward compatibility. We should remove this library once all its dependencies are gone, most notably the CreateSymbols tool and CombinationsTargetTest3 (which couldn't use ClassFile API due to a javac bug)