import org.hibernate.validator.valuehandling.UnwrapValidatedValue; //导入依赖的package包/类
private void checkAnnotations(Class<?> contractClass) {
    Field[] fields = contractClass.getFields();
    for (Field field : fields) {
        Class fieldType = field.getType();
        if (Optional.class.isAssignableFrom(fieldType)) {
            checkAnnotation(contractClass, field,UnwrapValidatedValue.class);
            checkNoAnnotation(contractClass, field, NotNull.class);
        }
        else {
            checkNoAnnotation(contractClass, field, UnwrapValidatedValue.class);
            checkAnnotation(contractClass, field,NotNull.class);
        }
    }

    for(Method method : contractClass.getMethods()) {
        if(method.isAnnotationPresent(AssertTrue.class) || method.isAnnotationPresent(AssertFalse.class)) {
            if(method.getReturnType() != boolean.class && method.getReturnType() != Boolean.class) {
                throw new IllegalStateException("AssertTrue or AssertFalse annotations must be placed above methods that return boolean value");
            }

            if(!method.getName().startsWith("is")) {
                throw new IllegalStateException("Methods annotated with AssertTrue or AssertFalse must start with \"is\"");
            }
        }
    }
}