code: public static FastStr of(char[] ca) {
          if (ca.length == 0) return EMPTY_STR;
          char[] newArray = new char[ca.length];
          System.arraycopy(ca, 0, newArray, 0, ca.length);
          return new FastStr(ca);
      }
docs: Construct a FastStr from a char array
  @param ca the char array
  @return a FastStr