Fixed a bug/typo in the subject field validation

Author: pavelgj

src/eventarc/eventarc-utils.ts

@@ -80,7 +80,7 @@ export function toCloudEventProtoFormat(ce: CloudEvent): any {
     });
   }
   if (ce.subject) {
-    if (!validator.isNonEmptyString(ce.datacontenttype)) {
+    if (!validator.isNonEmptyString(ce.subject)) {
       throw new FirebaseEventarcError(
         'invalid-argument', 
         "CloudEvent 'subject' if specified must be non-empty string.");

test/unit/eventarc/eventarc-utils.spec.ts

@@ -45,6 +45,7 @@ describe('eventarc-utils', () => {
       expect(utils.toCloudEventProtoFormat({
         type: 'some.custom.event',
         specversion: '1.0',
+        subject: 'context',
         datacontenttype: 'application/json',
         id: 'user-provided-id',
         data: {
@@ -64,6 +65,9 @@ describe('eventarc-utils', () => {
           },
           'time': {
             'ceTimestamp': '2022-03-16T20:20:42.212Z'
+          },
+          'subject': {
+            'ceString': 'context'
           }
         },
         'id': 'user-provided-id',