In older EL versions (< 3.0), it's not possible to use enum constants or any other static fields/methods in an EL expression as it is not really a good practive to create beans with getter/setter for each constants class, we provide an utils tag which allows to import enum values in a page.
The enum values can be accessed via the name of the class (default setting) or via a custom name (var attribute).
It also possible to get all enum values of the class with the "ALL_VALUES" suffix or a custom prefix via the "allSuffix" attribute.
<div class="card">
<p:importEnum type="javax.faces.application.ProjectStage" var="JsfProjectStages"
allSuffix="ALL_ENUM_VALUES"/>
<h5 class="mt-0">Development</h5>
<h:outputText value="#{JsfProjectStages.Development}" />
<h5>ALL</h5>
<ui:repeat var="current" value="#{JsfProjectStages.ALL_ENUM_VALUES}">
<h:outputText value="#{current}" styleClass="mb-2 block"/>
</ui:repeat>
</div>