How to use the @terrestris/ol-util/dist/WfsFilterUtil/WfsFilterUtil.getCombinedRequests function in @terrestris/ol-util

const searchOpts = {
      featureNS,
      featurePrefix,
      featureTypes,
      geometryName,
      maxFeatures,
      outputFormat,
      propertyNames,
      srsName,
      wfsFormatOptions,
      searchAttributes,
      attributeDetails
    };

    const request = WfsFilterUtil.getCombinedRequests(
      searchOpts, this.state.searchTerm
    );

    if (request) {
      this.setState({
        fetching: true
      }, () => {
        fetch(`${baseUrl}`, {
          method: 'POST',
          credentials: additionalFetchOptions.credentials
            ? additionalFetchOptions.credentials
            : 'same-origin',
          body: new XMLSerializer().serializeToString(request),
          ...additionalFetchOptions
        })
          .then(response => response.json())

const searchOpts = {
      featureNS,
      featurePrefix,
      featureTypes,
      geometryName,
      maxFeatures,
      outputFormat,
      propertyNames,
      srsName,
      wfsFormatOptions,
      searchAttributes,
      attributeDetails
    };

    const request = WfsFilterUtil.getCombinedRequests(
      searchOpts, this.state.searchTerm
    );

    if (request) {
      this.setState({
        fetching: true
      }, () => {
        fetch(`${baseUrl}`, {
          method: 'POST',
          credentials: additionalFetchOptions.credentials
            ? additionalFetchOptions.credentials
            : 'same-origin',
          body: new XMLSerializer().serializeToString(request),
          ...additionalFetchOptions
        })
          .then(response => response.json())