Align the teaching source and language contract with compact defaults

examples/release1/sa/behavior/scenario_sa_conversation.arcadia

@@ -1,7 +1,5 @@
 sa_scenario sa_conversation "Repair request and measured reply" id "730b27ca-b039-5a3b-8dc6-03418f9061b3" {
     context @sa_restore;
-    description "";
-    parent none;
     postcondition "The controller has received the measured pressure after repair";
     precondition "A pressure alarm has been assessed";
     steps [@sa_call, @sa_reply];
@@ -14,23 +12,17 @@ sa_occurrence sa_call "Request valve repair" id "8bab4783-a098-5984-9e36-493957c
             exchange @sa_contact;
             message_kind Call;
             receiver @sa_responder;
-            reply_to none;
             sender @sa_caller;
             values [{
                 expression "420.0";
                 field @sa_pressure_parameter;
-                path [];
             }];
         };
     };
-    description "";
     parent @sa_conversation;
-    postcondition "";
-    precondition "";
 }
 
 sa_lifeline sa_caller "Controller" id "98c61788-2fee-51f4-8cf9-de48e8c70e9e" {
-    description "";
     parent @sa_conversation;
     represented @sa_control;
 }
@@ -46,18 +38,13 @@ sa_occurrence sa_reply "Return pressure after repair" id "4e1c0a56-ce80-5f13-a93
             values [{
                 expression "320.0";
                 field @sa_pressure_parameter;
-                path [];
             }];
         };
     };
-    description "";
     parent @sa_conversation;
-    postcondition "";
-    precondition "";
 }
 
 sa_lifeline sa_responder "Technician" id "6249b54a-e396-5338-82b9-89266c55670d" {
-    description "";
     parent @sa_conversation;
     represented @sa_technician;
 }