Fixes NPE in TreeTable.setContainerDS(null) (#12928)

Change-Id: I7f3148e51d216dfe20a11c8a5fd922f43cbc673b

2 files changed, 17 insertions, 2 deletions

diff --git a/server/src/com/vaadin/ui/TreeTable.java b/server/src/com/vaadin/ui/TreeTable.java
index e150db9423..1c13eae8d9 100644
--- a/server/src/com/vaadin/ui/TreeTable.java
+++ b/server/src/com/vaadin/ui/TreeTable.java
@@ -590,11 +590,11 @@ public class TreeTable extends Table implements Hierarchical {
         // does not change component hierarchy during paint
         containerSupportsPartialUpdates = (newDataSource instanceof ItemSetChangeNotifier) && false;
 
-        if (!(newDataSource instanceof Hierarchical)) {
+        if (newDataSource != null && !(newDataSource instanceof Hierarchical)) {
             newDataSource = new ContainerHierarchicalWrapper(newDataSource);
         }
 
-        if (!(newDataSource instanceof Ordered)) {
+        if (newDataSource != null && !(newDataSource instanceof Ordered)) {
             newDataSource = new HierarchicalContainerOrderedWrapper(
                     (Hierarchical) newDataSource);
         }
diff --git a/server/tests/src/com/vaadin/tests/server/component/treetable/TreeTableSetContainerNull.java b/server/tests/src/com/vaadin/tests/server/component/treetable/TreeTableSetContainerNull.java
new file mode 100644
index 0000000000..a3b79a14f0
--- /dev/null
+++ b/server/tests/src/com/vaadin/tests/server/component/treetable/TreeTableSetContainerNull.java
@@ -0,0 +1,15 @@
+package com.vaadin.tests.server.component.treetable;
+
+import junit.framework.TestCase;
+
+import com.vaadin.ui.TreeTable;
+
+public class TreeTableSetContainerNull extends TestCase {
+
+    public void testNullContainer() {
+        TreeTable treeTable = new TreeTable();
+
+        // should not cause an exception
+        treeTable.setContainerDataSource(null);
+    }
+}