code: public static <T> T evaluate(ValueExpression expression, PageContext pageContext) {
          if (expression == null) {
              return null;
          }
          @SuppressWarnings("unchecked")
          T value = (T) expression.getValue(pageContext.getELContext());
          return value;
      }
docs: Evaluate a value expression. To support optional attributes, if the expression is null then
  null will be returned.
  
  @param expression the expression
  @param pageContext the context for the JSP
  @param <T> the expected type of the expression
  @return the result of evaluating the expression