It also states that Josh Bloch is one of the authors. You maybe right that he may have done this as not a work for hire, or even that he may still own copyrights for this code (I don't know what the contributors agreement said at that time), but Google didn't even contest it in court.
http://hg.openjdk.java.net/jdk7/jdk7/jdk/annotate/37a05a11f2...
It also states that Josh Bloch is one of the authors. You maybe right that he may have done this as not a work for hire, or even that he may still own copyrights for this code (I don't know what the contributors agreement said at that time), but Google didn't even contest it in court.