FileProvider with external folder

Question

I'm trying to open a file (using the FileProvider) that is stored in a private folder

File appFiles = new File(externalPath.getAbsolutePath() +
    "/Android/data/com.my.nice.domain/files/Container/");

Then inside the appFiles i'm creating subfolder and store files inside the sub folder

my files_path.xml looks like this

<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
    <external-path name="my_path4" 
        path="Android/data/com.my.nice.domain/files/Container/"/>
</paths>

Relevant manifest xml code snippet

<provider
    android:name="android.support.v4.content.FileProvider"
    android:authorities="com.my.nice.domain.fileprovider"
    android:exported="false"
    android:grantUriPermissions="true">
    <meta-data
        android:name="android.support.FILE_PROVIDER_PATHS"
        android:resource="@xml/file_paths" />
</provider>

and this is how I'm using the FileProvider to open the files (to view them with the default viewer)

File f = new File(url);
String AUTHORITY="com.my.nice.domain.fileprovider";
Uri uri = FileProvider.getUriForFile(getApplicationContext(), AUTHORITY, f);
Intent i = new Intent(Intent.ACTION_VIEW, uri);
startActivity(i);

but for some reason its not working, and I'm getting error saying that file not found

example for error message that I'm getting

File not found (content://com.my.nice.domain.fileprovider/my_path4/576feb25/535d8216.xlsx)

Any ideas on what am I doing wrong?