selectAll(): make private and return empty list instead of null

• Return empty list instead of null on unexpected input (null or wrong selection type)
• Fixes NPE in setSelection()

Issue-Ref: 3545 Issue-Url: https://af3-developer.fortiss.org/issues/3545

Signed-off-by: Simon Barner barner@fortiss.org

org.fortiss.tooling.kernel.ui/src/org/fortiss/tooling/kernel/ui/util/.ratings

@@ -7,7 +7,7 @@ EObjectSelectionUtils.java 128cf8f96c6b9478171dff3deda662d5934f5f44 GREEN
 KernelUIUtils.java 46d3279ef3523b104f89a6c526109f72d36f72f2 GREEN
 ObservableUtils.java 34abfd1dfaf9c0acbb31caf1f525e7b39416c116 GREEN
 PropertiesConstantUtils.java 59b1a1e4d594bb98db3aa396f2ff6474ba405920 GREEN
-SelectionUtils.java 33aec7cccccb28e5568140cf8e5443ce0f9f59f7 YELLOW
+SelectionUtils.java 33aec7cccccb28e5568140cf8e5443ce0f9f59f7 GREEN
 TutorialUIServiceUtils.java 093a8a3549c6952d44ea508e66691434b17a95b5 GREEN
 UndoRedoImpl.java f218500875bda0ef52f4cc2ccdf452825e6751f7 GREEN
 WidgetsFactory.java 5be121cc81e93731f4d0ab11e7707417fa950c2c GREEN