使用产品：iserver 10i 10.0.0a 操作系统：win10 x64
iClient版本: SuperMap iClient JavaScript 10i
问题详细描述：地图是发布在iServer的栅格瓦片地图, 使用地图列表中的浏览于 iClient for Leaflet 功能可以查看到1~20层级的各个元素.
但是使用如下代码却只能正常查看1~18层级元素, 19,20层级时地图一片空白
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title data-i18n="resources.title_tiledMapLayer4326"></title>
<script type="text/javascript" src="../js/include-web.js"></script>
</head>
<body style=" margin: 0;overflow: hidden;background: #fff;width: 100%;height:100%;position: absolute;top: 0;">
<div id="map" style="margin:0 auto;width: 100%;height: 100%"></div>
<script type="text/javascript" src="../../dist/leaflet/iclient9-leaflet.js"></script>
<script type="text/javascript">
var host = window.isLocal ? window.server : "https://iserver.supermap.io";
var map, url = host + "/iserver/services/map-world/rest/maps/World";
map = L.map('map', {
crs: L.CRS.EPSG4326,
center: [30, 105],
maxZoom: 20,
zoom: 7,
zoomControl:false
});
map.on('zoomend', function(e){
let zoom = e.target.getZoom();
console.log("当前层级: ", zoom)
});
// L.supermap.tiledMapLayer(url).addTo(map);
L.supermap.tiledMapLayer("http://127.0.0.1:8090/iserver/services/map-ugcv5-CDSLine/rest/maps/CDS_Line").addTo(map);
</script>
</body>
</html>
