code: public synchronized PacketBuilder withBytes(final byte[] b)
      {
          checkBuilt();
          try
          {
              dataOutputStream.writeInt(b.length);
              dataOutputStream.write(b);
          }
          catch (final IOException e)
          {
              logger.error("Unable to add bytes: {} : {}", e.getClass(), e.getMessage());
          }
          return this;
      }
docs: Adds byte array
  @param b Byte array
  @throws IllegalStateException see {@link #checkBuilt()}