code: private byte[] readTlvContent(TlvHeader header) throws IOException {
          byte[] data = new byte[header.getDataLength()];
          in.readFully(data);
          return data;
      }
docs: Reads the TLV content bytes from the underlying stream.
  
  @param header
  instance of {@link TlvHeader}, not null.
  
  @return TLV content bytes.
  
  @throws IOException
  if an I/O error occurs.