The document refers to upgrading from 2.1 to 3.0. It should be referring to upgrading to the latest version.

Document subtitle:
"JBoss Developer Studio 2.1 to 3.0."

Chapter 1. Introduction
"migrate from 2.1 to 3.0.0 JBoss Developer Studio."

Chapter 2 Migration process
"This chapter describes the JBoss Developer Studio migration from version 2.1 to 3.0. "

Sect 2.1
"2.1. How to migrate the JBoss Developer Studio from 2.1 to 3.0"
"To migrate from 2.1 to 3.0 you have to perform a new install of the JBoss Developer Studio 3.0"

"Since JBoss Developer Studio 3.0 uses a new version of Eclipse, an update from within Eclipse cannot be performed as it was when upgrading from JBoss Developer Studio 2.0 to 2.1. "

3.3. Problems with not "JBDS" plugins
"Some additional plugins that are not supplied by JBDS and work on JBDS 2.X may not work on 3.0.0.GA "

Version: JBoss_Developer_Studio-Migration_Guide-4.0-web-en-US-4.0.0-3.el5