AFAIK Android originally didn't use OpenJDK, but rather Apache Harmony, which is an IBM reimplementation of the Java JDK. So in that sense maybe Oracle does have a point (if API's are deemed to be copyrightable).

I think Android has since switched to OpenJDK, so it seems to me what Oracle and Google are arguing about is whether Google owes Oracle some damages for their previous use of Harmony. And of course, the lawsuit could have larger repercussions as well, if API's are deemed to be copyrightable.