erp5_json_rpc_api: use accessor

master/bt5/erp5_json_rpc_api/DocumentTemplateItem/portal_components/document.erp5.JsonRpcAPIService.py

@@ -124,7 +124,7 @@ class JsonRpcAPIService(OpenAPIService):
       # The convention is defined by the web service configuration only
       request_path = '/'.join(request_path_parts)
       matched_operation = None
-      for line in (self.getProperty('text_content') or '').split('\n'):
+      for line in self.getJsonFormList():
         if not line:
           continue