added another convenience method

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

@@ -876,16 +876,12 @@ public abstract class AbstractBuild<P extends AbstractProject<P,R>,R extends Abs
 
         return new Iterable<AbstractBuild<?, ?>>() {
             public Iterator<AbstractBuild<?, ?>> iterator() {
-                return new Iterators.FilterIterator<AbstractBuild<?,?>>(
-                        new AdaptedIterator<Integer,AbstractBuild<?,?>>(nums) {
-                            protected AbstractBuild<?, ?> adapt(Integer item) {
-                                return that.getBuildByNumber(item);
-                            }
-                        }) {
-                    protected boolean filter(AbstractBuild<?,?> build) {
-                        return build!=null;
-                    }
-                };
+                return Iterators.removeNull(
+                    new AdaptedIterator<Integer,AbstractBuild<?,?>>(nums) {
+                        protected AbstractBuild<?, ?> adapt(Integer item) {
+                            return that.getBuildByNumber(item);
+                        }
+                    });
             }
         };
     }

core/src/main/java/hudson/util/Iterators.java

@@ -272,6 +272,18 @@ public class Iterators {
         };
     }
 
+    /**
+     * Wraps another iterator and throws away nulls.
+     */
+    public static <T> Iterator<T> removeNull(final Iterator<T> itr) {
+        return new FilterIterator<T>(itr) {
+            @Override
+            protected boolean filter(T t) {
+                return t!=null;
+            }
+        };
+    }
+
     /**
      * Returns an {@link Iterable} that iterates over all the given {@link Iterable}s.
      *