For the record, the way I could work around this issue was as follows:
1) Download hplip-3.15.2-plugin.run and hplip-3.15.2-plugin.run.asc from http://www.openprinting.org/download/printdriver/auxfiles/HP/plugins/ as Chris2k suggests.
2) Kick off the Plug-in installer from the HP Device Manager.
3) Choose to install plug-in from a local file copy rather than downloading it from the server.
4) Proceed with installation as usual.
For the record, the way I could work around this issue was as follows:
1) Download hplip-3. 15.2-plugin. run and hplip-3. 15.2-plugin. run.asc from http:// www.openprintin g.org/download/ printdriver/ auxfiles/ HP/plugins/ as Chris2k suggests.
2) Kick off the Plug-in installer from the HP Device Manager.
3) Choose to install plug-in from a local file copy rather than downloading it from the server.
4) Proceed with installation as usual.