Merge pull request #3717 from runzexia/add-nonnull-annotations

add getDescriptorOrDie Nonnull annotations

core/src/main/java/jenkins/model/Jenkins.java

@@ -1511,6 +1511,7 @@ public class Jenkins extends AbstractCIBase implements DirectlyModifiableTopLeve
      *      If the descriptor is missing.
      * @since 1.326
      */
+    @Nonnull
     public Descriptor getDescriptorOrDie(Class<? extends Describable> type) {
         Descriptor d = getDescriptor(type);
         if (d==null)