OverDrive API Partners,
On 15-AUG-2017, OverDrive introduced the new URL syntax for our library websites in our Account and Search API responses. The main drive behind this change is to ensure users are always redirected to the most current version of a library website.
For more details on this change, you can review our announcement here.
Thanks for being an OverDrive API Partner.
-The OverDrive API Team