code: public JSONResource json(URI anUri, AbstractContent requestContent) throws IOException {
  		return doPOSTOrPUT(anUri, requestContent, createJSONResource());
  	}
docs: POST to a URI and parse the result as JSON
  
  @param anUri
  the URI to visit
  @param requestContent
  the content to POST to the URI
  @return
  @throws IOException
  if uri is wrong or no connection could be made or for 10 zillion other reasons