how to customize webix ajax api to upload file

Hello, i am trying to set up my filemanager with my own api endpoints like in the example above

webix.ui({
			rows:[
				{
					view:"filemanager",
					id:"files",
					handlers:{
						"upload" :'${API_URL}/api/documents'
					}
				}
			]
		});

for some reason it is not applyng my api, it is using predefined one /filemanager/samples/server, i am doing it in react application. The whole component look like

import React, { Component } from 'react';
import API_URL from '../../../../config';

export default class TableFilePivotWebx extends Component {
  render() {
    return (
      <div id="test____res" className={"TableFilePivotWebx"}></div>
    );
  }

  componentDidMount() {
    const { data } = this.props;
    if (!data || data.length === 0) return;
    const webix = window.webix;
    const id = 'file_pivot';
    const options = {
      container: document.getElementById('test____res'),
      id,

      rows: [
        {
          view: 'filemanager',
          data: _.cloneDeep(data),
          id: 'files',
          handlers: {
            'upload': API_URL+'/api/documents',
          },
        },
      ],
    };
    webix.ready(() => {
      this.ui = webix.ui(options);
    });


  }

  componentWillUnmount() {
    if (this.ui) {
      this.ui.destructor();
      this.ui = null;
    }
  }

  shouldComponentUpdate() {
    return false;
  }
}