Ionic alert controller: placeholder not working on input type file

I have an Ionic alert controller that contains an input of type file. I set the placeholder text in the input configuration, like this:

But when the alert is prompted a default text is shown as shown below:

Am I missing something to configure? By the way, how can I change the default text for the select file button?

According to Ionic Alert Controller documentation, Placeholder property only works for textual and numeric inputs.