Custom SelectionInput widget won't submit incident succesfully

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First of all, I would like to say that I am a newbie and I am not really sure if I need to customize the standard widget in order to change that or what is the best way to do it. I want to change the standard -- of the empty selection input to "Please Select" and don't know the best way to do it. The way I understand it is that by extending a widget you add more blocks of code. Because I want to change the already defined -- to Please Select I overrode the code keeping all