SQL & PL/SQL

Is it possible grant execute on a package to a role? The following snippet (run as SYS AS SYSDBA) demonstrates my problem.

SET SERVEROUTPUT ON SIZE 1000000;

CREATE USER foo_user IDENTIFIED BY foo;
GRANT CONNECT, UNLIMITED TABLESPACE TO foo_user;

CREATE USER bar_user IDENTIFIED BY bar;
GRANT CONNECT, UNLIMITED TABLESPACE TO bar_user;

CREATE OR REPLACE PACKAGE foo_user.foo_package AS
    PROCEDURE foo_procedure;
END;
/

CREATE OR REPLACE PACKAGE BODY foo_user.foo_package AS
    PROCEDURE foo_procedure AS
    BEGIN
        DBMS_OUTPUT.PUT_LINE('Ran foo_user.foo_package.foo_procedure');
    END foo_procedure;
END;
/

CREATE ROLE bar_role;
GRANT bar_role TO bar_user;
GRANT EXECUTE ON foo_user.foo_package TO bar_role;

CREATE TABLE bar_user.bar_table(bar_column NUMBER);

CREATE OR REPLACE TRIGGER bar_user.bar_table_bit
BEFORE INSERT ON bar_user.bar_table
FOR EACH ROW 
BEGIN
    foo_user.foo_package.foo_procedure;
END; 
/

INSERT INTO bar_user.bar_table (bar_column) VALUES (1);

The execute grant on foo_user.foo_package to bar_role works, however, the creation of the trigger which relies on the grant does not. If, however, I replace the grant to bar_role with a grant to bar_user the creation of the trigger works fine. So replacing

CREATE ROLE bar_role;
GRANT bar_role TO bar_user;
GRANT EXECUTE ON foo_user.foo_package TO bar_role;

with

GRANT EXECUTE ON foo_user.foo_package TO bar_user;

works fine.

Am I doing something wrong or is not possible to grant execute on a package to a role?