It is a custom showTimePicker to allow you set a selectableTimePredicate like you do in showDatePicker.
showCustomTimePicker(
context: context,
// It is a must if you provide selectableTimePredicate
onFailValidation: (context) => print('Unavailable selection'),
initialTime: TimeOfDay(hour: 2, minute: 0),
selectableTimePredicate: (time) =>
time.hour > 1 &&
time.hour < 14 &&
time.minute % 10 == 0).then((time) =>
setState(() => selectedTime = time?.format(context)))
You can see a complete sample in example/example.dart
file