Typo. This list is of JobProperty, not UserProperty.

core/src/main/java/hudson/model/Job.java

@@ -160,7 +160,7 @@ public abstract class Job<JobT extends Job<JobT, RunT>, RunT extends Run<JobT, R
     boolean keepDependencies;
 
     /**
-     * List of {@link UserProperty}s configured for this project.
+     * List of properties configured for this project.
      */
     // this should have been DescribableList but now it's too late
     protected CopyOnWriteList<JobProperty<? super JobT>> properties = new CopyOnWriteList<JobProperty<? super JobT>>();