The class file of the method content generated using Bytecode failed to load

[Milory]

I have been learning Javassist (VERSION: 3.30.2-GA)recently and have also learned how to use Bytecode content. I would like to write a simple introductory example, as follows:

    @Test
    @SneakyThrows
    @DisplayName("读取注解")
    public void test01() {
        // 创建 ClassPool 对象
        ClassPool pool = ClassPool.getDefault();

        // 创建新类
        CtClass ctClass = pool.makeClass("HelloWorld");

        // 创建新方法
        CtMethod ctMethod = new CtMethod(pool.get("java.lang.String"), "greet", new CtClass[]{}, ctClass);
        ctMethod.setModifiers(Modifier.PUBLIC);

        // 获取类的常量池
        ConstPool constPool = ctClass.getClassFile().getConstPool();

        // 创建 Bytecode 对象，关联常量池
        Bytecode bytecode = new Bytecode(constPool);

        // 生成字节码指令：将字符串 "Hello, World!" 加载到栈顶
        bytecode.addLdc("Hello, World!");

        // 添加返回指令
        bytecode.addOpcode(Opcode.ARETURN);

        // 将生成的字节码设置到方法中
        ctMethod.getMethodInfo().setCodeAttribute(bytecode.toCodeAttribute());

        // 将方法添加到类中
        ctClass.addMethod(ctMethod);

        Class<?> aClass = ctClass.toClass();
        Object object = aClass.newInstance();
        System.err.println(aClass.getDeclaredMethod("greet").invoke(object));

But I found that the execution failed, and the error exception message thrown is as follows:

javassist.CannotCompileException: by java.lang.ClassFormatError: Arguments can't fit into locals in class file HelloWorld

	at javassist.util.proxy.DefineClassHelper.toClass(DefineClassHelper.java:271)
	at javassist.ClassPool.toClass(ClassPool.java:1240)
	at javassist.ClassPool.toClass(ClassPool.java:1098)
	at javassist.ClassPool.toClass(ClassPool.java:1056)
	at javassist.CtClass.toClass(CtClass.java:1298)
	at org.lijin.javassist.test01.Bytecode06.test01(Bytecode06.java:61)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at java.util.ArrayList.forEach(ArrayList.java:1259)
	at java.util.ArrayList.forEach(ArrayList.java:1259)
Caused by: java.lang.ClassFormatError: Arguments can't fit into locals in class file HelloWorld
	at java.lang.ClassLoader.defineClass1(Native Method)
	at java.lang.ClassLoader.defineClass(ClassLoader.java:757)
	at java.lang.invoke.MethodHandle.invokeWithArguments(MethodHandle.java:627)
	at javassist.util.proxy.DefineClassHelper$Java7.defineClass(DefineClassHelper.java:177)
	at javassist.util.proxy.DefineClassHelper.toClass(DefineClassHelper.java:260)
	... 8 more

So I used CtMethod. make() to regenerate the class file and compared the binary content of the file, and found that there were differences between the two files:

I don't know if there is a problem with my Bytecode example or if it is a bug. Looking forward to your reply