Add default getEmptyValue for MultiSelect interface (#8420) (#8421)

* Add deafult getEmptyValue for MultiSelect interface (#8420) Added an default implementation for getEmptyValue to the MultiSelect interface.
vaadin · Feb 2, 2017 · ab207e8 · ab207e8
1 parent 0bbee6f
commit ab207e8
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Showing 2 changed files with 11 additions and 5 deletions.
diff --git a/server/src/main/java/com/vaadin/ui/AbstractMultiSelect.java b/server/src/main/java/com/vaadin/ui/AbstractMultiSelect.java
@@ -216,11 +216,6 @@ public void setValue(Set<T> value) {
         updateSelection(copy, new LinkedHashSet<>(getSelectedItems()));
     }
 
-    @Override
-    public Set<T> getEmptyValue() {
-        return Collections.emptySet();
-    }
-
     /**
      * Adds a value change listener. The listener is called when the selection
      * set of this multi select is changed either by the user or

diff --git a/server/src/main/java/com/vaadin/ui/MultiSelect.java b/server/src/main/java/com/vaadin/ui/MultiSelect.java
@@ -136,4 +136,15 @@ public default boolean isSelected(T item) {
      */
     public Registration addSelectionListener(
             MultiSelectionListener<T> listener);
+
+    /**
+     * MultiSelect empty value should always be an empty set by default and not
+     * {@code null}.
+     *
+     * @return An empty set, not {@code null}
+     */
+    public default Set<T> getEmptyValue() {
+        return Collections.emptySet();
+    }
+
 }