This is what section JSP.5.3 of the specification says:
The value of the name attribute in jsp:setProperty and jsp:getProperty will
refer to an object that is obtained from the pageContext object through its findAttribute method.
The object named by the name must have been �introduced� to the JSP processor using either the jsp:useBean action or a custom action with an
associated VariableInfo entry for this name. If the object was not introduced in this manner, the container implementation is recommended (but not required) to raise a translation error, since the page implementation is in violation of the specification.
Note � A consequence of the previous paragraph is that objects that are stored in, say, the session by a front component are not automatically visible to jsp:setProperty and jsp:getProperty actions in that page unless a jsp:useBean action, or some other action, makes them visible.
I have tested it in
tomcat and a transaltion error is thrown.