code: public static long copy(Reader input, StringBuilder output)
              throws IOException {
          return copy(input, output, new char[DEFAULT_BUFFER_SIZE]);
      }
docs: Transfers data from Reader into StringBuilder
  Uses {@link #DEFAULT_BUFFER_SIZE} to define buffer size
  
  @param input  Reader which would be read
  @param output StringBuilder which would be filled
  @return amount of bytes transferred
  @throws IOException