Add pipeline id attribute to BuildEvent class (#999)

Co-authored-by: Jeremie Bresson <jeremie.bresson@unblu.com>

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

@@ -6,7 +6,7 @@ import org.gitlab4j.api.models.User;
 import org.gitlab4j.api.utils.JacksonJson;
 
 /**
- * The documentation at: <a href="https://docs.gitlab.com/ee/user/project/integrations/webhooks.html#job-events">
+ * The documentation at: <a href="https://docs.gitlab.com/ee/user/project/integrations/webhook_events.html#job-events">
  * Job Events</a> is incorrect, this class represents the actual content of the Job Hook event.
  */
 public class BuildEvent extends AbstractEvent {
@@ -28,6 +28,8 @@ public class BuildEvent extends AbstractEvent {
     private Boolean buildAllowFailure;
     private String buildFailureReason;
     private Long projectId;
+
+    private Long pipelineId;
     private String projectName;
     private User user;
     private BuildCommit commit;
@@ -155,6 +157,14 @@ public class BuildEvent extends AbstractEvent {
         this.projectId = projectId;
     }
 
+    public Long getPipelineId() {
+        return pipelineId;
+    }
+
+    public void setPipelineId(Long pipelineId) {
+        this.pipelineId = pipelineId;
+    }
+
     public String getProjectName() {
         return projectName;
     }

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

@@ -12,6 +12,7 @@
 	"build_duration": 0.05880817,
 	"build_allow_failure": false,
 	"build_failure_reason": "unknown_failure",
+	"pipeline_id": 2366,	
 	"project_id": 3115610,
 	"project_name": "GitLab4J / test-project",
 	"user": {