Expression Language API

 EL is a simple language designed to meet the needs of the presentation
 layer in Java web applications.
 .
 It features:
  * A simple syntax restricted to the evaluation of expressions
  * Variables and nested properties
  * Relational, logical, arithmetic, conditional, and empty operators
  * Functions implemented as static methods on Java classes
  * Lenient semantics where appropriate default values and type conversions
    are provided to minimize exposing errors to end users