Scripting custom attributes

I am looking to get the value of a custom attribute in an script

dojo.provide("com.swm.chargeDomaine");
dojo.require("com.ibm.team.workitem.api.common.WorkItemAttributes");

(function() {
var WorkItemAttributes= com.ibm.team.workitem.api.common.WorkItemAttributes;

dojo.declare("com.swm.chargeDomaine", null, {

    getValue: function(attributeId, workItem, configuration) {
   
    
    console.log("custom Value : "+workItem.getLabel(WorkItemAttributes.???????)+" = "+workItem.getValue(WorkItemAttributes.?????));
}
});
})();