Description: https://github.com/material-components/material-components-android/blob/master/docs/components/DatePicker.md:

Subscribe to button clicks or dismiss events with the following calls:

picker.addOnPositiveButtonClickListener {
   // Respond to positive button click.
}
picker.addOnNegativeButtonClickListener {
   // Respond to negative button click.
}
picker.addOnCancelListener {
   // Respond to cancel button click.		<--
}
picker.addOnDismissListener {
   // Respond to dismiss events.
}

Expected behavior:

Subscribe to button clicks, cancel and dismiss events with the following calls:

picker.addOnPositiveButtonClickListener {
   // Respond to positive button click.
}
picker.addOnNegativeButtonClickListener {
   // Respond to negative button click.
}
picker.addOnCancelListener {
   // Respond to cancel events.			<--
}
picker.addOnDismissListener {
   // Respond to dismiss events.
}

See also: https://github.com/material-components/material-components-android/blob/master/docs/components/TimePicker.md:

Subscribe to positive button click, negative button click, cancel and dismiss events with the following calls:

picker.addOnPositiveButtonClickListener {
   // call back code
}
picker.addOnNegativeButtonClickListener {
  // call back code
}
picker.addOnCancelListener {
   // call back code
}
picker.addOnDismissListener {
   // call back code
}