Using Template Directives in REST Data Source is not working

I have created a simple example to test Template Directives in REST Data Sources for a presentation I'm giving. Everything is created on a free oracleapex.com Account. For this I've built the following two tables:

CREATE TABLE "JUR_PERS"

(	"NAME" VARCHAR2(240 CHAR) NOT NULL ENABLE,

"USTNR" VARCHAR2(11 CHAR) NOT NULL ENABLE,

"ID" RAW(16),

CONSTRAINT "JUR_PERS_PK" PRIMARY KEY ("ID")

USING INDEX  ENABLE

) ;
CREATE OR REPLACE EDITIONABLE TRIGGER "JUR_PERS_T"

before

insert on "JUR_PERS"

for each row

begin

if :new.id is null then

:new.id := sys_guid();

end if;

end;

/

ALTER TRIGGER "JUR_PERS_T" ENABLE;