Make the structures immutable

weblablib.py

@@ -1299,21 +1299,21 @@ def request_client_data(self):
         """
         Information provided in the beginning of the interaction (on_start): client_data
         """
-        return self._request_client_data
+        return ImmutableDict(self._request_client_data or {})
 
     @property
-    def start_date(self):
+    def request_server_data(self):
         """
-        Information provided in the beginning of the interaction (on_start): client_data
+        Information provided in the beginning of the interaction (on_start): server_data
         """
-        return self._start_date
+        return ImmutableDict(self._request_server_data or {})
 
     @property
-    def request_server_data(self):
+    def start_date(self):
         """
-        Information provided in the beginning of the interaction (on_start): server_data
+        Information provided in the beginning of the interaction (on_start): client_data
         """
-        return self._request_server_data
+        return self._start_date
 
     def add_action(self, session_id, action):
         """