Unable to retrieve image's download URL from Firebase Storage?

The code successfully uploads an image to Firebase Storage but doesn't give back the download URL. How can I fix this?

I get no exceptions and the image is uploaded. This following line (which is supposed to show the URL) is never executed, why? System.out.println("Upload success: " + downloadUri);

private void uploadFile() {
    if (mImageUri != null) {
        StorageReference fileReference = mStorageRef.child(System.currentTimeMillis()
                + "." + getFileExtension(mImageUri));

        fileReference.putFile(mImageUri).continueWithTask(new Continuation<UploadTask.TaskSnapshot, Task<Uri>>() {
            @Override
            public Task<Uri> then(@NonNull Task<UploadTask.TaskSnapshot> task) throws Exception {
                if (!task.isSuccessful()) {
                    throw task.getException();
                }

                // Continue with the task to get the download URL
                return mStorageRef.getDownloadUrl();
            }
        }).addOnCompleteListener(new OnCompleteListener<Uri>() {
            @Override
            public void onComplete(@NonNull Task<Uri> task) {
                if (task.isSuccessful()) {
                    Uri downloadUri = task.getResult();
                        System.out.println("Upload success: " + downloadUri);
                } else {
                    // Handle failures
                    // ...
                }
            }
        });

    } else {
        Toast.makeText(this, "No file selected", Toast.LENGTH_SHORT).show();
    }

}

from Unable to retrieve image's download URL from Firebase Storage?