docs: @Override
      public int getInContainerRowCount(BBContainer tupleData) {
          // according to TableOutputStream.cpp:TupleOutputStream::endRows() the row count is
          // at offset 4 (second integer)
          ByteBuffer bb = tupleData.b().duplicate();
          bb.position(getHeaderSize());
          bb.getInt(); // skip first four (partition id)
  
          return bb.getInt();
      }