#1594 Refresh action for refreshable parts fixed.

plugins/org.jkiss.dbeaver.core/plugin.xml

@@ -495,16 +495,13 @@
 
         <handler commandId="org.eclipse.ui.file.refresh" class="org.jkiss.dbeaver.ui.actions.navigator.NavigatorHandlerRefresh">
             <activeWhen>
-                <reference definitionId="org.jkiss.dbeaver.core.ui.navigator.part"/>
-            </activeWhen>
-            <enabledWhen>
                 <with variable="activePart">
                     <or>
                         <adapt type="org.jkiss.dbeaver.ui.navigator.INavigatorModelView"/>
                         <adapt type="org.jkiss.dbeaver.ui.IRefreshablePart"/>
                     </or>
                 </with>
-            </enabledWhen>
+            </activeWhen>
         </handler>
         <handler commandId="org.jkiss.dbeaver.core.export.data" class="org.jkiss.dbeaver.tools.transfer.handlers.DataExportHandler">
             <enabledWhen>

plugins/org.jkiss.dbeaver.model/src/org/jkiss/dbeaver/model/navigator/DBNDatabaseFolder.java

@@ -110,7 +110,7 @@ public class DBNDatabaseFolder extends DBNDatabaseNode implements DBNContainer,
         return getParentNode() instanceof DBSWrapper ? ((DBSWrapper)getParentNode()).getObject() : null;
     }
 
-    @NotNull
+    @Nullable
     @Override
     public DBPDataSource getDataSource()
     {