code: private void injectServletCallback(String method) {
          Label tryStart = new Label();
          Label tryEnd = new Label();
          Label catchStart = new Label();
          Label catchEnd = new Label();
  
          visitTryCatchBlock(tryStart, tryEnd, catchStart, "java/lang/NoClassDefFoundError");
          mark(tryStart); // try {
          loadArgs();
          invokeStatic(Type.getType(SERVLET_CALLBACK_TYPE), Method.getMethod(method));
          mark(tryEnd); // }
          visitJumpInsn(GOTO, catchEnd);
          mark(catchStart); // catch() {
          pop();
          mark(catchEnd); // }
      }
docs: Inject a callback to our servlet handler.
  
  @param method