Fix overriding imports (#702)

This resolves #698.

---------

Co-authored-by: Yuta Kasai <[email protected]>

Author: habara-k

generator/src/main/java/line/bot/generator/PythonNextgenCustomClientGenerator.java

@@ -1368,7 +1368,7 @@ private ModelsMap postProcessModelsMap(ModelsMap objs) {
                     modelsToImport.add("from " + packageName + ".models." + underscore(modelImport) + " import " + modelImport);
                 }
 
-                model.getVendorExtensions().putIfAbsent("x-py-model-imports", modelsToImport);
+                model.getVendorExtensions().put("x-py-model-imports", modelsToImport);
             }
         }
 

linebot/v3/messaging/models/text_message_v2.py

@@ -20,7 +20,6 @@
 
 from typing import Dict, Optional
 from pydantic.v1 import Field, StrictStr
-from linebot.v3.messaging.models.dict[str,_substitution_object] import Dict[str, SubstitutionObject]
 from linebot.v3.messaging.models.message import Message
 from linebot.v3.messaging.models.quick_reply import QuickReply
 from linebot.v3.messaging.models.sender import Sender