How add Caldroid to Xamarin

https://github.com/roomorama/Caldroid i want add this lib with this tutorial docs.xamarin.com/guides/android/advanced_topics/java_integration_overview/binding_a_java_library_(.jar)/offline.pdf It catch error "Hirondelle.Date4j.DateTime" не реализует член интерфейса "Java.Lang.IComparable.CompareTo(Java.Lang.Object)"

Please help issue this error)