added use cases to engagement

Author: dwasinge

src/main/java/com/redhat/labs/lodestar/models/Engagement.java

@@ -55,5 +55,6 @@ public class Engagement {
 
     private List<Artifact> artifacts;
     private String commitMessage;
+    private List<UseCase> useCases;
 
 }

src/main/java/com/redhat/labs/lodestar/models/UseCase.java

@@ -0,0 +1,19 @@
+package com.redhat.labs.lodestar.models;
+
+import lombok.AllArgsConstructor;
+import lombok.Builder;
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+@Data
+@Builder
+@NoArgsConstructor
+@AllArgsConstructor
+public class UseCase {
+
+    private String id;
+    private String title;
+    private String description;
+    private Integer order;
+
+}