cypher syntax fix for unit test

Author: jbarrasa

src/main/java/n10s/mapping/MappingUtils.java

@@ -105,7 +105,7 @@ public Stream<StringOutput> dropAll(@Name("namespace") String schemaUri) {
   public Stream<StringOutput> drop(@Name("graphElementName") String gElem)
       throws MappingDefinitionException {
     String cypher = "MATCH (mapns)<-[:_IN]-(elem:_MapDef { _key : $local }) DETACH DELETE elem "
-        + "RETURN count(elem) AS deletecount, size((mapns)<-[:_IN]-()) AS remaining, mapns ";
+        + "RETURN count(elem) AS deletecount, size([(mapns)<-[r:_IN]-() | r ]) AS remaining, mapns ";
     Map<String, Object> params = new HashMap<>();
     params.put("local", gElem);
     Result queryResult = tx.execute(cypher, params);