docs: public HashMap<AbstractExpression, Set<AbstractExpression> > getAllEquivalenceFilters()
      {
          HashMap<AbstractExpression, Set<AbstractExpression> > equivalenceSet =
                  new HashMap< >();
          ArrayDeque<JoinNode> joinNodes = new ArrayDeque<>();
          // Iterate over the join nodes to collect their join and where equivalence filter expressions
          joinNodes.add(this);
          while ( ! joinNodes.isEmpty()) {
              JoinNode joinNode = joinNodes.poll();
              joinNode.collectEquivalenceFilters(equivalenceSet, joinNodes);
          }
          return equivalenceSet;
      }