getTemplate(sViewId) {
					var oViewOverlay = OverlayRegistry.getOverlay(sViewId);
					if (!oViewOverlay) {
						throw DtUtil.createError("service.ControllerExtension#getTemplate", "no overlay found for the given view ID", "sap.ui.rta");
					}

					var sControllerExtensionTemplatePath = oViewOverlay.getDesignTimeMetadata().getControllerExtensionTemplate();
					return fetchTemplate(`${sControllerExtensionTemplatePath}-dbg`)
					.catch(function() {
						return fetchTemplate(sControllerExtensionTemplatePath);
					});
				}
Gets the controller extension template from the <code>DesignTimeMetadata</code> of the given view and returns it as a string wrapped in a promise.
If there is no template specified, a default template will be returned.

@method sap.ui.rta.service.ControllerExtension.getTemplate
@param {string} sViewId - ID of the view whose template should be retrieved
@return {Promise<string>} Promise that resolves with the template as string or rejects when the file was not found
@public