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src/android/src/main/java/com/RNFetchBlob/RNFetchBlobReq.java

 
             final Request req = builder.build();
 
+            // intercept network redirections
             clientBuilder.addNetworkInterceptor(new Interceptor() {
                 @Override
                 public Response intercept(Chain chain) throws IOException {

src/polyfill/File.js

 
   name : string = '';
 
-  static build(name:string, data:any, cType):Promise<File> {
+  static build(name:string, data:any, cType:string):Promise<File> {
     return new Promise((resolve, reject) => {
       new File(data, cType).onCreated((f) => {
         f.name = name