convertOssToW3C marked by Nullable

Author: TikhomirovSergey

src/main/java/org/openqa/selenium/remote/NewSessionPayload.java

@@ -428,7 +428,7 @@ public Object setValue(Object value) {
         return Stream.concat(fromOss, fromW3c).distinct();
     }
 
-    private Map<String, Object> convertOssToW3C(Map<String, Object> capabilities) {
+    private @Nullable Map<String, Object> convertOssToW3C(Map<String, Object> capabilities) {
         if (capabilities == null) {
             return null;
         }