public ImmutableBitSet getFactorsRefByJoinFilter(RexNode joinFilter) {
    return requireNonNull(
            factorsRefByJoinFilter.get(joinFilter),
            () -> "joinFilter is not found in factorsRefByJoinFilter: " + joinFilter);
  }
Returns a bitmap corresponding to the factors referenced within
the specified join filter.

@param joinFilter Filter for which information will be returned
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/rules/HiveLoptMultiJoin.java