ATLAS-4847 : Export/Import : Atlas export fails and throws NullPointerException

Signed-off-by: Pinal Shah <pinal.shah@freestoneinfotech.com>
diff --git a/repository/src/main/java/org/apache/atlas/repository/impexp/ExportService.java b/repository/src/main/java/org/apache/atlas/repository/impexp/ExportService.java
index 4615c6c..8ab071b 100644
--- a/repository/src/main/java/org/apache/atlas/repository/impexp/ExportService.java
+++ b/repository/src/main/java/org/apache/atlas/repository/impexp/ExportService.java
@@ -442,12 +442,13 @@
                 return ret;
             }
 
-            for (AtlasEntity entity : entityWithExtInfo.getReferredEntities().values()) {
-                if((doesTimestampQualify(entity))) {
-                    ret.add(entity);
+            if (entityWithExtInfo.getReferredEntities() != null) {
+                for (AtlasEntity entity : entityWithExtInfo.getReferredEntities().values()) {
+                    if((doesTimestampQualify(entity))) {
+                        ret.add(entity);
+                    }
                 }
             }
-
             return ret;
         }