Ian: release 2.8.0 contained a bug that erroneously put a database, by default, into a directory (.couchbase) different than the directory used by default in any other version. While this did not cause the loss of any data or make the data inaccessible, it absolutely broke existing applications and made them appear to lose data.
This bug was fixed in Android 2.8.1 and Java 2.8.3. Users of Android or Java 2.8.0 should be encouraged to upgrade immediately to avoid creating spurious database.
I think it is a mistake to promise anything about the location of the default database, in the documentation. We may need to move it again, in particular, to adapt to new versions of Android. Perhaps a comment: "by default, databases are created in the applications sandbox" is in order. Code, though, that appears to promise an implementation, seems like a bad idea to me.
Priya Rajagopal will, of course, have the last word on this.