code: public Collection<String> getAttributes() {
          J4pReadRequest request = getRequest();
          ObjectName requestBean = request.getObjectName();
          if (requestBean.isPattern()) {
              throw new IllegalArgumentException(
                      "Attributes can be fetched only for non-pattern request (current: " +
                              requestBean.getCanonicalName() + ")");
          }
          // The attribute names are the same as from the request
          if (request.hasSingleAttribute()) {
              // Contains only a single attribute:
              return request.getAttributes();
          } else {
              JSONObject attributes = getValue();
              return attributes.keySet();
          }
      }
docs: Get all attributes obtained. This method can be only used, if the requested MBean
  was not a pattern (i.e. the request was for a single MBean).
  
  @return a list of attributes for this request. If the request was performed for
  only a single attribute, the attribute name of the request is returend as
  a single valued list. For more than one attribute, the attribute names
  a returned from the returned list.