Good news for folks using their own Maven Repository Manager, as the two major players both add support to their products to allow proxying of the Oracle Maven Repository.
Nexus 2.11.2 (to be released soon) will have the necessary support included, and Artifactory 3.5.1 (available now) supports the Oracle Maven Repository.
In Artifactory, you just define the Oracle Maven Repository as a new remote repository, and provide the URL as shown below:
Then click on the Advanced Settings tab, provide a HTTP/SOCKS proxy if you need one to access the Internet, and enter your OTN credentials for the repository. Then, make sure you select the two options Lenient host authentication and Enable cookie management as shown below:
With these settings, Artifactory will happily proxy the Oracle Maven Repository for you.
I will post details of the configuration for Nexus when their new release becomes available.