onos-6308: avoiding null pointer exception in yobutils

Change-Id: I671a5b30ace6fdeb19411643b966cde3ffdf18ff
diff --git a/apps/yms/app/src/main/java/org/onosproject/yms/app/yob/YobUtils.java b/apps/yms/app/src/main/java/org/onosproject/yms/app/yob/YobUtils.java
index 749a801..e38836b 100644
--- a/apps/yms/app/src/main/java/org/onosproject/yms/app/yob/YobUtils.java
+++ b/apps/yms/app/src/main/java/org/onosproject/yms/app/yob/YobUtils.java
@@ -235,6 +235,7 @@
             interfaceClass = regClass.getClassLoader().loadClass(qualName);
         } catch (ClassNotFoundException e) {
             log.info(E_FAIL_TO_LOAD_CLASS, qualName);
+            return;
         }
 
         Class<?>[] innerClasses = interfaceClass.getClasses();