How to use the ngx-validators.UniversalValidators.noEmptyString function in ngx-validators

@Component({
  selector: 'app-reactive-universal-validator',
  templateUrl: './universal-validator.component.html',
  styleUrls: ['./universal-validator.component.css']
})
export class ReactiveFormUniversalValidatorComponent implements OnInit {

  form: FormGroup;
  noWhitespace: FormControl = new FormControl('', Validators.compose([
    Validators.required,
    UniversalValidators.noWhitespace
  ]));

  noEmptyString: FormControl = new FormControl('', Validators.compose([
    Validators.required,
    UniversalValidators.noEmptyString
  ]));

  min: FormControl = new FormControl('', Validators.compose([
    Validators.required,
    UniversalValidators.min(5)
  ]));

  max: FormControl = new FormControl('', Validators.compose([
    Validators.required,
    UniversalValidators.max(10)
  ]));

  isNumber: FormControl = new FormControl('', Validators.compose([
    Validators.required,
    UniversalValidators.isNumber
  ]));