Updated error message in function test

Change-Id: I89f5310b01f0a26cc534b353f85a45e51ccd5c25
Signed-off-by: Botond Baranyi <botond.baranyi@ericsson.com>

function_test/Semantic_Analyser/encode/encode_SE.ttcn

@@ -54,7 +54,7 @@ with {
   variant (f3) "untagged"; //Variant attribute is not related to JSON encoding//
 }
 
-type record Rec5 { //^In type definition// //Invalid attribute, 'as value' is only allowed for unions, the anytype, or records or sets with one field//
+type record Rec5 { //^In type definition// //Invalid attribute, 'as value' is only allowed for unions, the anytype, or records or sets with one mandatory field//
   integer f1, //Invalid attribute, 'omit as null' requires optional field of a record or set.//
   Rec4 f2, //USE-UNION can only be applied to a CHOICE/union type//
   record of Rec3 f3 //Invalid attribute, 'name as ...' requires field of a record, set or union.// //Invalid JSON default value for type `@encode_SE.Rec5.f3'. Only the empty array is allowed.//