code: public int getBlockLength(final DirectBuffer buffer, final int bufferOffset)
      {
          return Types.getInt(buffer, bufferOffset + blockLengthOffset, blockLengthType, blockLengthByteOrder);
      }
docs: Get the block length of the root block in the message.
  
  @param buffer       from which to read the value.
  @param bufferOffset in the buffer at which the message header begins.
  @return the length of the root block in the coming message.