Oracle owns copyright on OpenJDK, so it can't 'violate'. Maybe more precisely, if you regard the API in question as copyrightable, Oracle has clearly licensed

Oracle owns copyright on OpenJDK, so it can't 'violate'. Maybe more precisely, if you regard the API in question as copyrightable, Oracle has clearly licensed it under GPLv2 plus the Classpath Exception. Also, the issue of copyrightability of the Java SE API has already been definitively decided in this case, in Oracle's favor.