code: public boolean isAnnotationPresent(Class<? extends Annotation> annotationClass) {
          boolean result = false;
          if (field != null) {
              result = field.isAnnotationPresent(annotationClass);
          }
          if (!result && setter != null) {
              result = setter.isAnnotationPresent(annotationClass);
          }
          if (!result && getter != null) {
              result = getter.isAnnotationPresent(annotationClass);
          }
          return result;
      }
docs: 是否有该注解
  
  @param annotationClass
  @return