Check channel creadentials for merged config

temba/channels/views.py

@@ -425,18 +425,11 @@ def add_config_field(self, config_key: str, field, *, default):
         self.fields[config_key] = field
         self.config_fields.append(config_key)
 
-    def creds_config(self, cleaned_data: dict, extra: dict) -> dict:
-        """
-        Transform form data credentials to config format dict
-        """
-        config = cleaned_data.copy()
-        config.update(**extra)
-        return config
-
     def clean(self) -> dict[str, Any]:
         cleaned_data = super().clean()
-        credentials_config = self.creds_config(cleaned_data, {})
-        if not Channel.get_type_from_code(self.object.channel_type).check_credentials(credentials_config):
+        updated_config = self.object.config | cleaned_data
+
+        if not Channel.get_type_from_code(self.object.channel_type).check_credentials(updated_config):
             raise ValidationError(_("Channel credentials don't appear to be valid."))
         return cleaned_data