From: <david.delabassee_at_oracle.com>
Date: Sun, 21 Sep 2014 04:26:33 +0000 (UTC)

There's a note on the 1st page of the 1st chapter of the Administration
Guide, see https://glassfish.java.net/docs/4.0/administration-guide.pdf

---
Note: For the zip bundle of GlassFish Server 4.0, the default
administrator login is admin, with no password, which means that no
login is required.
---
Should put it on the cover? ;-)
I have prepared an Aquarium entry to reiterate this.