How to use the abap-adt-api.isGroupType function in abap-adt-api

private async validateObject(objDetails: NewObjectOptions) {
    let validateOptions: ValidateOptions
    if (isGroupType(objDetails.objtype))
      validateOptions = {
        description: objDetails.description,
        fugrname: objDetails.parentName,
        objname: objDetails.name,
        objtype: objDetails.objtype as GroupTypeIds
      }
    else if (objDetails.objtype === PACKAGE && hasPackageOptions(objDetails)) {
      validateOptions = {
        description: objDetails.description,
        objname: objDetails.name,
        objtype: objDetails.objtype as PackageTypeId,
        packagename: objDetails.parentName,
        swcomp: objDetails.swcomp,
        packagetype: objDetails.packagetype,
        transportLayer: objDetails.transportLayer
      }