code: public static String repeat(String source, int times) {
          dbc.precondition(source != null, "cannot repeat a null source");
          dbc.precondition(times > -1, "times must be non negative");
          final int srcLen = source.length();
          final long longLen = times * (long) srcLen;
          final int len = (int) longLen;
          dbc.precondition(longLen == len, "resulting String would be too long");
          final char[] array = new char[len];
          for (int i = 0; i != times; ++i) {
              source.getChars(0, srcLen, array, i * srcLen);
          }
          return new String(array);
      }
docs: Creates a String by repeating the source string.
  
  @param source the source String
  @param times times the source String will be repeated
  @return the resulting string