I have troubles like this as well with Windows and Linux machines. I believe that JBoss is asking the operating system for it's hostname and the os resolver is giving the short name instead of what you really wanted...the fully qualified domain name.
What you might try is editting the /etc/host file on your Solaris box so that the FQDN is listed first on the line for the host's IP address instead of the alias. This has worked for me on Linux as I recall. Other apps also suffer until I make that change (mysql comes to mind) .....the default for RedHat is to list the alias first and then the FQDN. Either way is correct, but the resolver will give the first name listed when queried. I would expect the Solaris resolver to react the same.
Of course if you have your resolver configured differently, e.g to use NIS, this may not work.