OAK-11607 fix test failures

Author: joerghoh

oak-core/src/main/java/org/apache/jackrabbit/oak/plugins/tree/impl/OrderedChildnameIterable.java

@@ -65,11 +65,9 @@ public OrderedChildnameIterator (Iterable<String> orderedChildren, Iterable<Stri
             nextResult = getNextElement();
         }
 
-        String getNextElement() {
-            String elem = null;
-
+        private String getNextElement() {
             if (orderedChildren.hasNext()) {
-                elem = getNextOrderedChild();
+                String elem = getNextOrderedChild();
                 if (elem != null) {
                     return elem;
                 }
@@ -83,7 +81,7 @@ String getNextElement() {
             if (nonOrderedChildrenIterator.hasNext()) {
                 return nonOrderedChildrenIterator.next();
             }
-            // return all children which have not been consumed from the allChildren iterator yet
+            // return all children which have not been consumed from the allChildren iterator
             if (allChildren.hasNext()) {
                 return allChildren.next();
             }
@@ -92,8 +90,8 @@ String getNextElement() {
         }
 
         /**
-         * Consume the next element from the orderedChild list
-         * @return null if no ordered child can be retrieved, otherwise the next ordered child name
+         * Consume the next element from the orderedChild list and validates that it's actually present
+         * @return the next ordered child or  {code null} if all ordered children have already been returned
          */
         String getNextOrderedChild() {
             String current = null;
@@ -102,6 +100,8 @@ String getNextOrderedChild() {
                 current = orderedChildren.next();
                 if (isOrderedChildPresent(current)) {
                     return current;
+                } else {
+                    current = null; // skip this element, as it's not present in the allChildren iterator
                 }
             }
             return null;

oak-core/src/test/java/org/apache/jackrabbit/oak/plugins/tree/impl/OrderedChildnameIterableTest.java

@@ -91,7 +91,7 @@ public void orderedChildren() {
     @Test
     public void orderedChildrenWithNonExistingOrderedChild() {
         // the ordered list contains a non-existing childname, which is not part of children list
-        OrderedChildnameIterable iterable = new OrderedChildnameIterable(List.of("4","5","nonexisting"),ALL_CHILDREN);
+        OrderedChildnameIterable iterable = new OrderedChildnameIterable(List.of("4","nonexisting1","5","nonexisting2"),ALL_CHILDREN);
         Assert.assertEquals(List.of("4","5","1","2","3"), iterableToList(iterable));
     }