I always ran into issues when updating jdeveloper extensions after a fresh install. The standard steps are: Jdeveloper -> help -> check for udpates, then select the extensions you need.
Although I don't have proxy, but a popup always asks me to use this proxy "emeacache.uk.oracle.com", I uncheck proxy, the update ended up doing nothing.
It didn't help, their "official" extension center (http://www.oracle.com/ocom/groups/public/@otn/documents/webcontent/131167.xml) doesn't even have the SOA composite editor :(
Well, for today, this is how it is "working" for me: like I said, I do not use proxy from my network to internet, but after numerous failed attempts, i finally logged onto a VPN. It beats me that within the VPN, the update actually worked! Go figure! I'm logging it here, in case, I have to go through the same thing in 6 month again...