!include once #1019934 // BCEL

import org.apache.bcel.classfile.Attribute;
import org.apache.bcel.classfile.SourceFile;
import org.apache.bcel.generic.*;

svoid changeJavaVersionInClassFile(File classFile, int newMajor, int newMinor) ctex {
  JavaClass c = new ClassParser(classFile.getPath(), classFile.getName()).parse();
  int major = c.getMajor(), minor = c.getMinor();
  print("Current Java version of " + classFile + ": " + major + "." + minor);
  if (major == newMajor && minor == newMinor) ret;
  print("  Patching to " + newMajor + "." + newMinor);

  ClassGen g = new ClassGen(c);
  g.setMajor(newMajor);
  g.setMinor(newMinor);
  c = g.getJavaClass();
  c.dump(classFile); // overwrite!
  print("  Done");
}

Began life as a copy of #1004069