code: public static String[] splitByCharacterTypeCamelCase(final String str) {
          if (str == null) {
              return null;
          }
          if (str.isEmpty()) {
              return new String[0];
          }
          final char[] c = str.toCharArray();
          final List<String> list = new ArrayList<>();
          int tokenStart = 0;
          int currentType = Character.getType(c[tokenStart]);
          for (int pos = tokenStart + 1; pos < c.length; pos++) {
              final int type = Character.getType(c[pos]);
              if (type == currentType) {
                  continue;
              }
              if (type == Character.LOWERCASE_LETTER && currentType == Character.UPPERCASE_LETTER) {
                  final int newTokenStart = pos - 1;
                  if (newTokenStart != tokenStart) {
                      list.add(new String(c, tokenStart, newTokenStart - tokenStart));
                      tokenStart = newTokenStart;
                  }
              } else {
                  list.add(new String(c, tokenStart, pos - tokenStart));
                  tokenStart = pos;
              }
              currentType = type;
          }
          list.add(new String(c, tokenStart, c.length - tokenStart));
          return list.toArray(new String[0]);
      }
docs: <p>Splits a String by Character type as returned by
  {@code java.lang.Character.getType(char)}. Groups of contiguous
  characters of the same type are returned as complete tokens, with the
  following exception: if {@code camelCase} is {@code true},
  the character of type {@code Character.UPPERCASE_LETTER}, if any,
  immediately preceding a token of type {@code Character.LOWERCASE_LETTER}
  will belong to the following token rather than to the preceding, if any,
  {@code Character.UPPERCASE_LETTER} token.
  @param str the String to split, may be {@code null}
  @return an array of parsed Strings, {@code null} if null String input
  @since 2.4