fix(entities): enum map throws exception for empty maps (#195)

* fix(entities): enum map throws exception for empty maps

* fix(entities): enum map throws exception for empty maps

Author: skjindal93

gateway-service-impl/src/main/java/org/hypertrace/gateway/service/entity/query/ExecutionTreeBuilder.java

@@ -10,7 +10,7 @@
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
-import java.util.EnumMap;
+import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -330,7 +330,7 @@ QueryNode buildAndFilterTree(EntitiesRequest entitiesRequest) {
     }
 
     Map<AttributeSource, Filter> sourceToAndFilterMap =
-        new EnumMap<>(buildSourceToAndFilterMap(entitiesRequest.getFilter()));
+        new HashMap<>(buildSourceToAndFilterMap(entitiesRequest.getFilter()));
 
     // qs node as the pivot node to fetch time range data
     QueryNode qsNode =