This sentence says to me that PatternHandler is going to add anchors around your regex (^ at the front and $), since that's how it would ensure that the entire message matched the regex. But the example shows the developer already including anchors, which would be unnecessary if that were the case.  Also, I would argue against the PatternHandler doing that anyway. It's better if the developer has the flexibility to include the anchors or not, depending on whether they want to match the whole message.