Consider .jsp file source with failure: 

<c:set var="class" value="foo" />
${class}

Another case:
I have a bean with getter: boolean isNew() available in jsp under name foo. 
The following .jsp crashes:
<c:if test="${foo.new}">AAA</c:if>

The same issues are found in .tag files. 
I included c prefix taglib with 
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>

Is there a workaround to add a prefix for all variable names in generated java code in order to make my application working with Tomcat7 without changes? My application works under Tomcat6.