Add source attribute to PipelineEvent.ObjectAttributes (#466)

src/main/java/org/gitlab4j/api/webhook/PipelineEvent.java

@@ -75,6 +75,7 @@ public class PipelineEvent extends AbstractEvent {
         private Boolean tag;
         private String sha;
         private String beforeSha;
+        private String source;
         private String status;
         private List<String> stages;
         private Date createdAt;
@@ -122,6 +123,14 @@ public class PipelineEvent extends AbstractEvent {
             this.beforeSha = beforeSha;
         }
 
+        public String getSource() {
+            return source;
+        }
+
+        public void setSource(String source) {
+            this.source = source;
+        }
+
         public String getStatus() {
             return status;
         }

src/test/resources/org/gitlab4j/api/pipeline-event.json

@@ -6,6 +6,7 @@
       "tag": false,
       "sha": "bcbb5ec396a2c0f828686f14fac9b80b780504f2",
       "before_sha": "bcbb5ec396a2c0f828686f14fac9b80b780504f2",
+      "source": "merge_request_event",
       "status": "success",
       "stages":[
          "build",
@@ -154,4 +155,4 @@
          }
       }
    ]
-}
+}
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