#2184 - Fix for findNative() with fetch() - convert fetch to fetchQuery with nativeSql

When using nativeSql (think of it as the "root query") we can't use "fetch joins" (FetchConfig.ofDefault()) as that means to prefer to use a SQL JOIN. In this nativeSql case we need to effectively automatically convert fetch() to fetchQuery()

ebean-core/src/main/java/io/ebeaninternal/server/querydefn/DefaultOrmQuery.java

@@ -1441,6 +1441,10 @@ public class DefaultOrmQuery<T> implements SpiQuery<T> {
 
   @Override
   public Query<T> fetch(String path, String properties, FetchConfig config) {
+    if (nativeSql != null && (config == null || config.isJoin())) {
+      // can't use fetch join with nativeSql (as the root query)
+      config = FETCH_QUERY;
+    }
     return fetchInternal(path, properties, config);
   }