Cesium GeoJSON update

HTML

<script src="https://cesiumjs.org/Cesium/Build/Cesium/Cesium.js"></script>
<link rel="stylesheet" href="https://cesiumjs.org/Cesium/Build/Cesium/Widgets/widgets.css">
<div id="cesiumContainer"></div>

CSS

html {
          height: 100%;
      }
      body {
          padding: 0;
          margin: 0;
          overflow: hidden;
          height: 100%;
      }

JavaScript

var viewer = new Cesium.Viewer('cesiumContainer');

function dataCallback(interval, index) {
    var time;
    if (index === 0) { // leading
        time = Cesium.JulianDate.toIso8601(interval.stop);
    } else {
        time = Cesium.JulianDate.toIso8601(interval.start);
    }

    return {
        Time: time
    };
}

var times = Cesium.TimeIntervalCollection.fromIso8601({
    iso8601: '2015-07-30/2017-06-16/P1D',
    leadingInterval: true,
    trailingInterval: true,
    isStopIncluded: false, // We want stop time to be part of the trailing interval
    dataCallback: dataCallback
});

// Add a WMTS imagery layer
var provider = new Cesium.WebMapTileServiceImageryProvider({
    url : 'https://gibs.earthdata.nasa.gov/wmts/epsg4326/best/AMSR2_Snow_Water_Equivalent/default/{Time}/{TileMatrixSet}/{TileMatrix}/{TileRow}/{TileCol}.png',
    layer : 'AMSR2_Snow_Water_Equivalent',
    style : 'default',
    tileMatrixSetID : '2km',
    maximumLevel : 5,
    format : 'image/png',
    clock: viewer.clock,
    times: times,
    credit : new Cesium.Credit('NASA Global Imagery Browse Services for EOSDIS')
});
var imageryLayers = viewer.imageryLayers;
imageryLayers.addImageryProvider(provider);
provider.readyPromise
    .then(function() {
        var start = Cesium.JulianDate.fromIso8601('2015-07-30');
        var end = Cesium.JulianDate.fromIso8601('2017-06-17');

        viewer.timeline.zoomTo(start, end);

        var clock = viewer.clock;
        clock.startTime = start;
        clock.endTime = end;
        clock.currentTime = start;
        clock.clockRange = Cesium.ClockRange.LOOP_STOP;
        clock.multiplier = 86400;
    });