account for null reference names in validation

Author: mrahanjam

format-common/src/main/java/io/cdap/plugin/format/plugin/AbstractFileSinkConfig.java

@@ -85,7 +85,9 @@ public void validate(FailureCollector collector) {
   }
 
   public void validate(FailureCollector collector, Map<String, String> arguments) {
-    IdUtils.validateReferenceName(referenceName, collector);
+    if (!Strings.isNullOrEmpty(referenceName)) {
+      IdUtils.validateReferenceName(referenceName, collector);
+    }
     if (suffix != null && !containsMacro(NAME_SUFFIX)) {
       try {
         new SimpleDateFormat(suffix);

format-common/src/main/java/io/cdap/plugin/format/plugin/AbstractFileSourceConfig.java

@@ -141,7 +141,9 @@ public void validate() {
   }
 
   public void validate(FailureCollector collector) {
-    IdUtils.validateReferenceName(referenceName, collector);
+    if (!Strings.isNullOrEmpty(referenceName)) {
+      IdUtils.validateReferenceName(referenceName, collector);
+    }
     try {
       getSchema();
     } catch (IllegalArgumentException e) {