Feature Request: Provide a new function 'IsInit' in PropertyInfo to test the new init of c#9

[moh-hassan]

c# 9 introduced an Init-only properties 'init'.
Example:

public class Person
{
    public string FirstName { get; init; }
    public string LastName { get; init; }
}

It's needed to test if the property has Init using reflection.
@YairHalberstadt provide a solution

bool IsInitOnly(PropertyInfo propertyInfo)
{
    return propertyInfo.SetMethod.ReturnParameter.GetRequiredCustomModifiers().Any(x => x.FullName == typeof(System.Runtime.CompilerServices.IsExternalInit).FullName);
}

It's nice if BCL contain a property to test 'Init' like:

bool isInit= propertyInfo.SetMethod.IsInit