--- a/trytond/trytond/convert.py	Tue May 28 10:03:40 2019 +0200
+++ b/trytond/trytond/convert.py	Thu May 30 09:37:52 2019 +0200
@@ -242,7 +242,7 @@
                     context.update(CONTEXT)
                 value = eval(eval_attr, context)
                 if pyson_attr:
-                    value = PYSONEncoder().encode(value)
+                    value = PYSONEncoder(sort_keys=True).encode(value)
                 self.values[field_name] = value
 
         else: