How to pass an object to a custom tag [in Spring MVC]?

Question

In Spring MVC, my code returns a ModelAndView with the model being object of class Foo.
Class Foo has a method

public Zoo getZoo()

In the JSP view i would like to pass the model object's Zoo to a custom tag. I have a custom tag named doForObject, (which should do some reflection on the passed object). The corresponding tag Class has

public void setObject(Object object) {
    this.object = object;
}

How do I pass Foo's Zoo to this custom tag?
I tried both this:

<my:doForObject object="${model.zoo" />

as well as

<my:doForObject>
    <jsp:attribute name="object">${model.zoo}</jsp:attribute>
</my:doForObject>

and even this didn't work

<c:set var="obj" value="${model.zoo}" />
<my:doForObject object="${obj}" />

but in all 3 cases i get errors when the JSP is invoked.
For example, for the last attempt i got the error message

According to TLD or attribute directive in tag file, attribute object does not accept any expressions

The model object (instance of Foo) was created (for simplicity) as follows:

Foo foo = new Foo();
Zoo zoo = new Zoo();
foo.setZoo(zoo);