Index: trunk/test/unit/org/openstreetmap/josm/actions/RestorePropertyActionTest.java
===================================================================
--- trunk/test/unit/org/openstreetmap/josm/actions/RestorePropertyActionTest.java	(revision 17996)
+++ trunk/test/unit/org/openstreetmap/josm/actions/RestorePropertyActionTest.java	(revision 17996)
@@ -0,0 +1,49 @@
+// License: GPL. For details, see LICENSE file.
+package org.openstreetmap.josm.actions;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import javax.swing.DefaultListSelectionModel;
+import javax.swing.ListSelectionModel;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+import org.openstreetmap.josm.command.ChangePropertyCommand;
+import org.openstreetmap.josm.data.UndoRedoHandler;
+import org.openstreetmap.josm.data.coor.LatLon;
+import org.openstreetmap.josm.data.osm.DataSet;
+import org.openstreetmap.josm.data.osm.Node;
+import org.openstreetmap.josm.testutils.JOSMTestRules;
+
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
+
+/**
+ * Unit tests of {@link RestorePropertyAction}
+ */
+class RestorePropertyActionTest {
+
+    /**
+     * Setup test.
+     */
+    @RegisterExtension
+    @SuppressFBWarnings(value = "URF_UNREAD_PUBLIC_OR_PROTECTED_FIELD")
+    public JOSMTestRules test = new JOSMTestRules().preferences();
+
+    @Test
+    void testTicket20965() {
+        doTest20965(null, null);
+        doTest20965("key", null);
+        doTest20965(null, "val");
+        doTest20965("key", "val");
+    }
+
+    private static void doTest20965(String key, String val) {
+        ListSelectionModel selModel = new DefaultListSelectionModel();
+        selModel.setSelectionInterval(1, 2);
+        Node n = new Node(LatLon.NORTH_POLE);
+        new DataSet(n);
+        UndoRedoHandler.getInstance().clean();
+        new RestorePropertyAction(k -> key, v -> val, () -> n, selModel).actionPerformed(null);
+        assertTrue(UndoRedoHandler.getInstance().getLastCommand() instanceof ChangePropertyCommand);
+    }
+}