Allow ITriggers with nullable properties (#1685)

Author: enzocano

lib/typescript/botbuilder-skills/src/models/skillManifest.ts

@@ -45,9 +45,9 @@ export interface IActionDefinition {
  * Definition of the triggers for a given action within a Skill.
  */
 export interface ITriggers {
-    utterances: IUtterance[];
+    utterances?: IUtterance[];
     utteranceSources: IUtteranceSources[];
-    events: IEvent[];
+    events?: IEvent[];
 }
 
 /**

lib/typescript/botbuilder-skills/src/skillManifestGenerator.ts

@@ -134,6 +134,10 @@ export class SkillManifestGenerator {
                             });
                         });
 
+                        if (action.definition.triggers.utterances === undefined) {
+                            action.definition.triggers.utterances = [];
+                        }
+
                         action.definition.triggers.utterances.push({
                             locale: utteranceSource.locale,
                             text: utterancesToAdd