At the risk of creating a firestorm:

1) The download-manager API now works, so that's good, but...
2) JBossTools cannot use the installer jar. We can only use the zip file.

Assuming this doesn't hurt others' usecases, we kindly request the URL be changed to https://www.jboss.org/download-manager/jdf/file/jboss-eap-6.3.0.GA.zip

PR to come soon