[FIX] Convertion from HASH_TABLE keys to JSON

.gitignore

@@ -0,0 +1 @@
+*.swp

library/kernel/converters/json_hash_table_converter.e

@@ -71,7 +71,11 @@ feature -- Conversion
             until
                 c.after
             loop
+                if attached {JSON_STRING} json.value (c.key) as l_key then
+                    js := l_key
+                else
                     create js.make_json (c.key.out)
+                end
                 jv := json.value (c.item)
                 if jv /= Void then
                     Result.put (jv, js)