Update JSON_VALUE and JSON_OBJECT interface

json/json_object.e

@@ -66,14 +66,12 @@ feature -- Access
 		end
 
 	get_keys:ARRAY[JSON_STRING] is
-			--
+			-- array containing actually used keys
 		do
 			Result:=object.current_keys
 		end
 
 
-
-
 feature -- Report
 	to_json:STRING is
 			--  Printable json representation