Messages from Accounting are private, and so they are sent to the individual brokers. You will not see them in the logs unless you have an external broker logged in, and you have the BrokerProxyService logging at the debug level. What, exactly, were you looking for?
I found out finally that was I was searching was the ArrayList message sent to me.
I think that the structure of the message is confusing. It would be much better if it created an CashUpdate type of message, for example, giving the information in a correct way and not something that obsure, in my humble opinion.
I don't know if this can be done now at the last time, but I was pretty buffled by it.
For the time being at least, the version in the master branch does not embed messages in lists, but I'm not sure that's a good idea. It can greatly increase the number of individual messages that have to be handled.
The rule is that every incoming message is either a message instance (of a type defined in powertac-common) or a list containing message instances. So if you get a list, you just have to iterate over it.