function marshallCustomIdentifiersHelper(result, params, shape) {
	  if (!shape || params === undefined || params === null) return;
	  if (shape.type === 'structure' && shape.required && shape.required.length > 0) {
	    util.arrayEach(shape.required, function(name) {
	      var memberShape = shape.members[name];
	      if (memberShape.endpointDiscoveryId === true) {
	        var locationName = memberShape.isLocationName ? memberShape.name : name;
	        result[locationName] = String(params[name]);
	      } else {
	        marshallCustomIdentifiersHelper(result, params[name], memberShape);
	      }
	    });
	  }
	}
Recursive helper for marshallCustomIdentifiers().
Looks for required string input members that have 'endpointdiscoveryid' trait.
@api private