code: public Boolean getCondition(FacesContext context) {
  
          if (conditionExpr == null && condition != null) {
              ExpressionFactory factory =
                    context.getApplication().getExpressionFactory();
              conditionExpr = factory.createValueExpression(context.getELContext(),
                                                            condition,
                                                            Boolean.class);
          }
  
          return ((conditionExpr != null)
                  ? (Boolean) conditionExpr.getValue(context.getELContext())
                  : null);
  
      }
docs: <p class="changed_added_2_0">Evaluates the
  <code>&lt;if&gt;</code> for this
  <code>&lt;navigation-case&gt;</code>, if any.  The expression to
  be evaluated is passed into the constructor as a string.  When
  the expression is evaluated, its value must be coerced into a
  <code>boolean</code> per the normal EL coercion rules.</p>
  
  @param context the {@link FacesContext} for the current request
  
  @return <code>null</code> if there is no <code>&lt;if&gt;</code> element
  associated with this <code>&lt;navigation-case&gt;</code>, otherwise
  return the evaluation result of the condition
  
  @throws any exceptions encountered during the process of
  evaluating the expression or obtaining its value.