bs.cs

private enum Kind { Get, Set };

private static string InterfaceGetOrSetMethod(PropertyInfo propertyInfo, Kind kind)
{
    var kindString = Kind == Kind.Get ? "get" : "set";

    if (propertyInfo.GetMethod == null)
        return "";

    var accessModifier = propertyInfo.Accessmodifier();
    var methodAccessModifier = propertyInfo.GetMethod.Accessmodifier();

    if (methodAccessModifier == accessModifier)
        return kindString + ";";
    return methodAccessModifier.ToString().ToLower() + kindString + ";";
}

public static string InterfaceGetMethod(this PropertyInfo propertyInfo)
{
    return InterfaceGetOrSetMethod(propertyInfo, Kind.Get);
}

public static string InterfaceSetMethod(this PropertyInfo propertyInfo)
{
    return InterfaceGetOrSetMethod(propertyInfo, Kind.Set);
}