Validators are not working

[jlberrocal]

As per the lack of time picker in angular/material i decided to use this library, however i just notice that validations are not being trigger in the input

how to reproduce it? using angular material (matInput) add the required validator to a formControl, then clean the input field (deal with the modal). As you may notice the required error is never triggered, if it help you i'm using a custom validator to check the min time