Big sigh… Expanding on this always makes me feel like I should just keep quiet. 
"Adapters do not connect directly to the Broker in the 6.0 environment " By this I meant, the 6.x architecture is designed to support JCA adapters hosted from the Adapter Runtime of the Integration Server. There is no connection to the Broker required for these adapters to work.
However, it is possible in 6.x to deploy not just the new architecture JCA adapters, but also old-style IS (4.6 and earlier) adapters and the old-style Broker (5.0 and earlier) adapters. No Broker connection is required for JCA or IS adapters, though a Broker connection would be required for the Broker adapters.
Personally, I would try to avoid connecting a Broker adapter to a 6.x Broker, but rather go the route of a 6.x Broker in a territory alongside a 5.0 Broker in a separate territory, sharing documents via a gateway…
As I understand it, webMethods wants to move away from the old-style Broker adapters, and even the old-style IS adapters, in favor of the JCA adapters.
#webMethods#Flow-and-Java-services#Integration-Server-and-ESB