If it’s NOT a String literal, it’s evaluated
If there are no quotes inside the brackets, the Container evaluates what’s inside the brackets by searching for an attribute bound under that name, and substitutes the value of the attribute. (If there is an implicit object with the same name, the implicit object will always be used.)
Find an attribute named “Ambient”. Use the VALUE of that attribute as the key into the Map, or return null.
In a servlet
This does NOT work in a JSP (given the servlet code)