Add global node_id to GHObject + GHTeam extends GHObject

src/main/java/org/kohsuke/github/GHObject.java

@@ -28,6 +28,7 @@ public abstract class GHObject {
 
     protected String url;
     protected long id;
+    protected String node_id;
     protected String created_at;
     protected String updated_at;
 
@@ -123,6 +124,17 @@ public abstract class GHObject {
         return id;
     }
 
+    /**
+     * Get Global node_id from Github object.
+     * 
+     * @see <a href="https://developer.github.com/v4/guides/using-global-node-ids/">Using Global Node IDs</a>
+     * 
+     * @return Global Node ID.
+     */
+    public String getNodeId() {
+        return node_id;
+    }
+
     @SuppressFBWarnings(value = "UPM_UNCALLED_PRIVATE_METHOD", justification = "Bridge method of getId")
     private Object longToStringOrInt(long id, Class type) {
         if (type == String.class)