code: public static int countCodePoint(char source[], int start, int limit) {
          if (source == null || source.length == 0) {
              return 0;
          }
          return findCodePointOffset(source, start, limit, limit - start);
      }
docs: Number of codepoints in a UTF16 char array substring
  
  @param source UTF16 char array
  @param start Offset of the substring
  @param limit Offset of the substring
  @return number of codepoint in the substring
  @exception IndexOutOfBoundsException If start and limit are not valid.