code: public static void appendHexString(StringBuilder buffer, byte[] bytes) {
          assertNotNull(buffer);
          if (bytes == null) {
              return;     // do nothing (a noop)
          }
          appendHexString(buffer, bytes, 0, bytes.length);
      }
docs: Appends a byte array to a StringBuilder with each byte in a "Big Endian"
  hexidecimal format. For example, a byte 0x34 will be appended as a
  String in format "34".  A byte array of { 0x34, 035 } would append "3435".
  @param buffer The StringBuilder the byte array in hexidecimal format
  will be appended to.  If the buffer is null, this method will throw
  a NullPointerException.
  @param bytes The byte array that will be converted to a hexidecimal String.
  If the byte array is null, this method will append nothing (a noop)