https://docs.oracle.com/javase/jp/11/docs/api/java.base/java/time/chrono/ChronoPeriod.html
ChronoPeriod (Java SE 11 & JDK 11 )
java sejdk
https://developer.android.com/reference/kotlin/java/time/chrono/ChronoPeriod.html
ChronoPeriod | API reference | Android Developers
api referenceandroiddevelopers