Adding rows to a table for powerbi embed using Nuget

For posting rows using Nuget (for powerbi embedded), what are the differences between the two parameters below, and what should I provide for them? An example for requestMessage and customHeaders will be helpful. Thanks  

requestMessage, type: Object

customHeaders, type: Dictionary<String, List<String>>

 

Documentation for posting rows can be found here:

https://docs.microsoft.com/en-us/dotnet/api/microsoft.powerbi.api.v1.idatasets.postrowswithhttpmessagesasync?view=powerbiapi-1.1.10