The java.time.* are the new classes (IIRC, based on joda-time), but there are also the old time libraries in java.util.* and java.text.*. I don't know which ones the parent poster was talking about, but it might be the old ones.
The java.time libraries are available on android starting API level 26 https://developer.android.com/reference/java/time/package-su...
That is android 11, released in September of 2020 which is not widely distributed.
Does anyone know why the delay? It looks like Java 8 language features finally became compatible through some compatibility layer in Gradle 4.
Was it because of the lawsuits?