As we all know the groupheader list iitem aggregation has only title property .

Here I’m extending it with an icon aggregation . Create a new folder control->IGroupHeaderListItem.js

/*eslint-disable */
sap.ui.define([
	"sap/m/GroupHeaderListItem"
], function (List) {
	"use strict";

	/**
	 * Constructor for a new OTTOInput
	 */
	var IGroupHeaderListItem = List.extend("ZFOCS_ORDER.ext.control.IGroupHeaderListItem", {
		metadata: {
			aggregations: {

				rightIcon: {
					type: "sap.ui.core.Icon",
					multiple: false
				}
			}
		},
		init: function () {

		},
		renderer: function (oRm, oControl) {
			oRm.openStart("tr", oControl);
			oRm.addClass("sapMLIB sapMLIB-CTX sapMLIBShowSeparator sapMLIBTypeInactive sapMLIBFocusable sapMGHLI changePointer")
			oRm.writeClasses();
			oRm.openEnd();
			oRm.openStart("td", oControl);
			oRm.addClass("sapMGHLICell changePointer");
			oRm.writeClasses();
			oRm.openEnd();
			oRm.openStart("div", oControl);
			oRm.addClass("sapMLIBContent");
			oRm.writeClasses();
			oRm.openEnd();
			oRm.openStart('span', oControl);
			oRm.addClass("sapMGHLITitle");
			oRm.writeClasses();
			oRm.openEnd();
			oRm.write(oControl.getTitle());
			oRm.close('span');
			oRm.openStart('span', oControl);
			oRm.addClass("sapUiTinyMarginBegin sapUiTinyMarginTop");
			oRm.writeClasses();
			oRm.openEnd();
			oRm.renderControl(oControl.getRightIcon());
			oRm.close('span');
			oRm.close('div');
			oRm.close('td');
			oRm.close('tr');

		},
		onAfterRendering: function () {
			if (sap.ui.core.Control.prototype.onAfterRendering) {
				sap.ui.core.Control.prototype.onAfterRendering.apply(this, arguments);
			}
		}

	});

	return IGroupHeaderListItem;

});

Wile using it in controller use it like this

	grpHdrListItem = new IGroupHeaderListItem({
					title: sometitle,
						rightIcon:{
							src:"sap-icon://puzzle",
						}
				}).addStyleClass("somecolor");