code: @Nonnull
      public Query addAttribute(@Nonnull String attributeName) {
          return addAttribute(new QueryAttribute(attributeName, null, null));
      }
docs: Create a basic {@link QueryAttribute}, add it to the list attributes of this query
  and maintains the reverse relation (see {@link org.jmxtrans.embedded.QueryAttribute#getQuery()}).
  
  @param attributeName attribute to add
  @return this