code: HashMap<AbstractExpression, Set<AbstractExpression>> analyzeValueEquivalence() {
          // collect individual where/join expressions
          m_joinTree.analyzeJoinExpressions(m_noTableSelectionList);
          return m_joinTree.getAllEquivalenceFilters();
      }
docs: Collect value equivalence expressions across the entire SQL statement
  @return a map of tuple value expressions to the other expressions,
  TupleValueExpressions, ConstantValueExpressions, or ParameterValueExpressions,
  that they are constrained to equal.