docs: protected void produceCopyForTransformation(AbstractPlanNode copy) {
          copy.m_outputSchema = m_outputSchema;
          copy.m_hasSignificantOutputSchema = m_hasSignificantOutputSchema;
          copy.m_outputColumnHints = m_outputColumnHints;
          copy.m_estimatedOutputTupleCount = m_estimatedOutputTupleCount;
          copy.m_estimatedProcessedTupleCount = m_estimatedProcessedTupleCount;
  
          // clone is not yet implemented for every node.
          assert(m_inlineNodes.size() == 0);
          assert(m_isInline == false);
  
          // the api requires the copy is not (yet) connected
          assert (copy.m_parents.size() == 0);
          assert (copy.m_children.size() == 0);
      }