exporterconfig file format

I'm trying to use the -exporterconfig option with Win 10 version of WpaExporter.exe, so that I can specify multiple profiles with different time ranges, and get the following error:

Windows Performance Analyzer 10.0.10240.16384 (th1.150709-1700)
Could not deserialize file
The given exporter configuration file could not be exported.

This happens even with a simple config file like this:

{       "TraceNames" : [{                     "Key" : "trace1",                     "Value" : MyTraceFile.etl"              }       ],       "Profiles" : [{                     "Name" : "MyProfileFile.wpaProfile",                     "Traces" : [{                                  "Name" : "trace1",                                  "Slot" : 1                           }                     ]              }       ]
}

Could you tell me what is wrong with my config file or would you be able to provide an example of a working exportconfig file please?