2.9 introduced a new type StringMessageMap. When added in commit 76aff58919dc5030367ea24c7c8ef42dca3b75cd, there were a few checks for instanceof this new type. Consequently, old code that uses StructuredDataMessages are processed differently. In some cases, such messages are not logged at all. To fix this, the type checks should be generalized to the root base class – MapMessage.