Iterable<String> tempkeys;
        tempkeys=  rel.getPropertyKeys();
        while (tempkeys.iterator().hasNext()){
            String key = tempkeys.iterator().next();
            System.out.println(key);
        }

ArrayList<String> tempkeys;
        tempkeys= (ArrayList<String>) rel.getPropertyKeys();
        for (int i=0;i<=tempkeys.size();i++) {
            String key = tempkeys.iterator().next();
            System.out.println(key);
        }

try (Transaction tx = this.graphDb.beginTx()) {
        Node Node1 = JavaCluster.AddUniqueNode("Element", "Name", "Node1");
        Node Node2 = JavaCluster.AddUniqueNode("Element", "Name", "Node2");
        RelationshipType tt = DynamicRelationshipType.withName("rt");
        Relationship rel = Node1.createRelationshipTo(Node2, tt);
        rel.setProperty("prop1", "propval1");
        rel.setProperty("prop2", "propval2");
        ArrayList<String> tempkeys;
        tempkeys= (ArrayList<String>) rel.getPropertyKeys();
        for (int i=0;i<=tempkeys.size();i++) {
            String key = tempkeys.iterator().next();
            System.out.println(key);
        }
        tx.success();
    } catch (Exception e) {
        System.out.println("Error - exception " + e.toString());
        //throw new TransactionFailException("Transaction failed",e);

    }