Logging hookEnvent key instead of the entire object

src/main/java/com/cloudbees/jenkins/plugins/bitbucket/hooks/NativeServerPullRequestHookProcessor.java

@@ -87,7 +87,7 @@ public void process(HookEventType hookEvent, String payload, BitbucketType insta
                 eventType = SCMEvent.Type.UPDATED;
                 break;
             default:
-                LOGGER.log(Level.INFO, "Unknown hook event {0} received from Bitbucket Server", hookEvent);
+                LOGGER.log(Level.INFO, "Unknown hook event {0} received from Bitbucket Server", hookEvent.getKey());
                 return;
         }