code: public static byte[] enhanceModel(byte[] byteCode, Version modelVersion, ClassLoader... loaders)
          throws IOException, CannotCompileException {
          CtClass cc = doModelModifications(byteCode, modelVersion, loaders);
          if (cc == null) {
              return null;
          }
          byte[] newClass = cc.toBytecode();
          cc.defrost();
          cc.detach();
          return newClass;
      }
docs: Try to enhance the object defined by the given byte code. Returns the enhanced class or null, if the given class
  is no model, as byte array. There may be class loaders appended, if needed.