code: @Override
    public void readFixed(byte[] bytes, int start, int length) throws IOException {
      int i = in.read(bytes, start, length);
      if (i < length) {
        throw new EOFException();
      }
    }
docs: A fixed is decoded by just reading length bytes, and placing the bytes read
  into the bytes array, starting at index start.
  
  @param bytes
  The bytes array to populate.
  @param start
  The index in bytes to place the read bytes.
  @param length
  The number of bytes to read.