code: public byte[] composeString(byte oldString[], byte newString) {
          int length = oldString.length;
          byte string[] = new byte[length + 1];
          System.arraycopy(oldString, 0, string, 0, length);
          string[length] = newString;
          
          return string;
      }
docs: Append <code>newString</code> to the end of <code>oldString</code>.