code: public URIBuilder addParameter( String key, String value )
      {
          if ( key != null && value != null ) {
              queryParams.put( key, value );
          }
  
          return this;
      }
docs: Add a single query parameter. Parameter is ignored if it has null value.
  
  @param key The parameter key (not url encoded)
  @param value The parameter value (not url encoded)
  @return The builder