Primefaces 4.0-SNAPSHOT filterBy new syntax issue

Primefaces 4.0-SNAPSHOT filterBy new syntax issue

In Primefaces 4.0, the syntax for the filterBy attribute has changed. In
the demo code they list the 3.x and the 4.x syntax. Basically it boils
down to changing :
<p:column filterBy="#{var.property}"> ...
to:
<p:column filterBy="property"> ...
That's all great, however we use a Map in the backing bean, which used to
work really well in 3.5:
<p:column filterBy="#{utilityBean.vendorMap[var.id]}"> ...
My question is how do I accomplish the same thing with the new syntax ?