That's a run-of-the-mill attempt to deny copying. However, if you look at the synopsis documents I produced (with a decompiled version of Oracle's code on the left side and the code found in the Android codebase on the right side), you can see that Google grossly overstates the importance of those differences.
Here's one example (and the others are consistent with this): http://www.docstoc.com/docs/69702407/1-AclEntryImpl-synopsis