Re: JSTL: getting a map's keys

Can anyone help me figure out why the following is happening, or further
experiments I can run? (I have workarounds but I'd like to know what I'm
misunderstanding.)

Given:
- SimTable, a subclass of HashTable that defines getKeys() to call keyset()
- a session variable "data" which is a HashTable with "rates" set to an
instance of a SimTable

Why does ${rates.keys} generate nothing in these lines of JSP?

<c:set var="rates" value='${data["rates"]}'/>

<p>rates: ${rates}</p>

<p>jstl: ${rates.keys}</p>

<p>jsp: <%= ((edu.northwestern.ils.simulator.SimTable)
pageContext.findAttribute("rates")).getKeys() %></p>

Here's the generated HTML output:

<p>rates: {Bill=100.0, Fred=75.0, Jane=75.0, Mary=50.0, Sam=75.0,
Sarah=150.0}</p>

<p>jstl: </p>

<p>jsp: [Bill, Fred, Jane, Mary, Sam, Sarah]</p>