Annotate classes at runtime with ByteBuddy

Helper.java

// add @JsonDeserialize(using = JsonDeserializer.None.class) to classes
        // inspired by https://stackoverflow.com/a/49320259/1638047
        @SneakyThrows
        Class<? extends ManagementResource> annotateResourceClass(Class<? extends ManagementResource> clazz) {
            ClassPool classPool = ClassPool.getDefault();

            CtClass ctClass = classPool.get(clazz.getName());
            if (ctClass.isFrozen()) {
                return clazz;
            }
            ClassFile classFile = ctClass.getClassFile();
            ConstPool constPool = classFile.getConstPool();

            final String annotationAttr = AnnotationsAttribute.visibleTag;
            final AnnotationsAttribute attr = Optional.ofNullable((AnnotationsAttribute) classFile.getAttribute(annotationAttr))
                .orElse(new AnnotationsAttribute(constPool, annotationAttr));

            // do not re-create annotation if already attached to the class
            final String annotationClassName = JsonDeserialize.class.getName();
            final Annotation annotation = Optional.ofNullable(attr.getAnnotation(annotationClassName))
                .orElse(new Annotation(annotationClassName, constPool));
            annotation.addMemberValue("using", new ClassMemberValue(JsonDeserializer.None.class.getName(), constPool));
            attr.addAnnotation(annotation);

            classFile.addAttribute(attr);

            final byte[] byteCode = ctClass.toBytecode();
            final String target = clazz.getName().replace('.', '/');
            final ClassFileTransformer cft = new ClassFileTransformer() {
                @Override
                public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined,
                                        ProtectionDomain protectionDomain, byte[] classfileBuffer) {
                    if (target.equals(className)) {
                        return byteCode;
                    }
                    return null;
                }
            };
            try {
                instrumentation.addTransformer(cft, true);
                instrumentation.retransformClasses(clazz);
            } finally {
                instrumentation.removeTransformer(cft);
            }

            return clazz;
        }

pom.xml

<dependency>
    <groupId>org.javassist</groupId>
    <artifactId>javassist</artifactId>
    <version>3.25.0-GA</version>
</dependency>
<dependency>
    <groupId>net.bytebuddy</groupId>
    <artifactId>byte-buddy-agent</artifactId>
    <version>3.25.0-GA</version>
</dependency>