This issue is rewritten by

Yeah, detection is done for Glassfisj 3.1.x;
v2.1 is not supported...

Igor, just FYI, seems this is throwing an exception in Glassfish 2.1.1:

hence hot deploy won't be available for that server. In my case it isn't a problem (I am using cluster), but probably can be for others...

Passed manual testing using the following steps:

1. Start Glassfish with Liferay

2. Disable Auto Deploy

   • Domain > Applications Configuration > Auto Deploy = unflag

3. Restart Glassfish with Liferay

4. Assert that "Server does not support hot deploy" displays in logs

5. Deploy plugin

6. Assert that plugin does not show in Liferay

   • Add > More... > [plugin]

7. Enable Auto

8. Assert that plugin does not show in Glassfish

   • Application

   • Deploy Domain > Applications Configuration > Auto Deploy = flag

9. Restart Glassfish with Liferay

10. Assert that "Server supports hot deploy" displays in logs

11. Deploy plugin

12. Assert that plugin shows in Glassfish

    • Application

13. Assert that plugin shows in Liferay

    • Add > More... > [plugin]

Verified on:
Tomcat 7.0.27 + MySQL 5.1. 6.1.1 CE GIT ID: fe708510b1566583870a6be892d86f1761a1e64b
Tomcat 7.0.27 + MySQL 5.1. 6.1.20 EE GIT ID: a4e4deb86cd53686a028af844196c2abce0389e7
Tomcat 7.0.27 + MySQL 5.1. 6.2.X GIT ID: cee7fd455c421675afe193e0938ad5bbd0459a14

Addendum to steps

You should not use the auto.deploy.enabled property. It should remain true, as it is by default.

Instead of setting that portal property in your steps, you have to enable/disable hot-deployment feature of the application server. i.e. of the glassfish. So, when I said in my steps: "start glassfish with hotdeploy DISABLED" I meant to disable hot deploy feature in the glassfish (through admin console):

http://www.liferay.com/community/wiki/-/wiki/Main/Glassfish+tips#section-Glassfish+tips-Enable/Disable+auto-deploy