Text payloads (typically resulting from an XSLT transformation) are represented in Synapse using OMSourcedElement nodes backed by TextFileDataSource objects. Nodes of this type can potentially contain a large amount of data. When a message containing this kind of payload hits the LogMediator in 'full' mode, the entire content will be dumped, potentially causing problems for large payloads, in particular because the entire message is transformed to a String object. In this case, LogMediator should skip the text content in some way.
A proper solution would be to use the mechanism described in
WSCOMMONS-287 and let the LogMediator use an OMOutputFormat object with a custom property that would instruct TextFileDataSource to skip the serialization of the text content. However, currently the implementation of this solution is blocked by WSCOMMONS-335.