This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
Well, the documentation doesn't specify the answer to your question. There's mention of a "buffer" which to me sounds like an orderly queue of messages, but if that isn't enough then you could examine the source code.