replace www with UnityWebRequest

com.unity.uiwidgets/Runtime/engine2/AndroidPlatformUtil.cs

 using System;
 using System.IO;
 using System.Runtime.InteropServices;
+using UnityEngine.Networking;
 using NativeBindings = Unity.UIWidgets.ui.NativeBindings;
 namespace Unity.UIWidgets.engine2 {
     public static class AndroidPlatformUtil {
         internal static string unpackFile(string file) {
             var dir = Application.temporaryCachePath + "/";
             if (!File.Exists(dir + file)) {
-                WWW unpackerWWW = new WWW("jar:file://" + Application.dataPath + "!/assets/" + file);
-                while (!unpackerWWW.isDone) {
-                } // This will block in the webplayer.
+                var path = "jar:file://" + Application.dataPath + "!/assets/" + file;
+                using(var unpackerWWW = UnityWebRequest.Get(path)) {
+                    unpackerWWW.SendWebRequest();
+                    while (!unpackerWWW.isDone) {
+                    } // This will block in the webplayer.
+                    if (unpackerWWW.isNetworkError || unpackerWWW.isHttpError) {
+                        Debug.Log($"Failed to get file \"{path}\": {unpackerWWW.error}");
+                        return "";
+                    }
+                    var data = unpackerWWW.downloadHandler.data;
+                    FileInfo fileInfo = new System.IO.FileInfo(dir + file);
+                    fileInfo.Directory.Create();
+                    File.WriteAllBytes(fileInfo.FullName,  data);
-                if (!string.IsNullOrEmpty(unpackerWWW.error)) {
-                    Debug.Log("Error unpacking 'jar:file://" + Application.dataPath + "!/assets/" + file +
-                              "'");
-                    dir = "";
-                    return dir + file;
+                    throw new Exception("not loaded");
-                System.IO.FileInfo fileInfo = new System.IO.FileInfo(dir + file);
-                fileInfo.Directory.Create();
-                System.IO.File.WriteAllBytes(fileInfo.FullName,  unpackerWWW.bytes);
             }
 
             return dir + file;

com.unity.uiwidgets/Runtime/painting/image_provider.cs

 using System;
 using System.Collections;
 using System.Collections.Generic;
-using System.IO;
 using System.Text;
 using Unity.UIWidgets.async2;
 using Unity.UIWidgets.engine2;
 #else
             var path = "file://" + Path.Combine(Application.streamingAssetsPath, key.file);
 #endif
-            WWW unpackerWWW = new WWW(path);
-            while (!unpackerWWW.isDone) {
-            } // This will block in the webplayer.
-           
-            if (unpackerWWW.bytes.Length > 0) {
-                return decode(unpackerWWW.bytes);
-            }
+            using(var unpackerWWW = UnityWebRequest.Get(path)) {
+                unpackerWWW.SendWebRequest();
+                while (!unpackerWWW.isDone) {
+                } // This will block in the webplayer.
+                if (unpackerWWW.isNetworkError || unpackerWWW.isHttpError) {
+                    throw new Exception($"Failed to get file \"{path}\": {unpackerWWW.error}");
+                }
-            throw new Exception("not loaded");
+                var data = unpackerWWW.downloadHandler.data;
+                if (data.Length > 0) {
+                    return decode(data);
+                }
+
+                throw new Exception("not loaded");
+            }
         }
 
         IEnumerator _loadBytes(FileImage key) {