Right now, each data structure, that is build from a TSP REST call stores in the 'others' field all serialized parameters, that are not specified in the TSP but still be serialized by the server implementation.
This was initially, to be able to get more information that is used internally in the Trace Compass server, but not "officially" specified in the TSP.
If some data is needed to be transferred between server and client over the TSP, then it needs to properly specified in the TSP and the client and server can support it.