code: private static boolean isWhitespace( StringBuilder builder ) {
          for( int i = 0; i < builder.length(); i++ ) {
              if( !Character.isWhitespace( builder.charAt( i ) ) ) {
                  return false;
              }
          }
          return true;
      }
docs: If the builder is empty or contains only whitespaces
  
  @param builder
  the builder.
  @return true if there is no content