docs: public boolean indexAppliesTo( JoinCondition condition ) {
          if (condition instanceof ChildNodeJoinCondition) {
              return indexAppliesTo((ChildNodeJoinCondition)condition);
          }
          if (condition instanceof DescendantNodeJoinCondition) {
              return indexAppliesTo((DescendantNodeJoinCondition)condition);
          }
          if (condition instanceof EquiJoinCondition) {
              return indexAppliesTo((EquiJoinCondition)condition);
          }
          if (condition instanceof SameNodeJoinCondition) {
              return indexAppliesTo((SameNodeJoinCondition)condition);
          }
          return false;
      }