b <- list(
  ExtractionRequest = list(
    odata.type = "#ThomsonReuters.Dss.Api.Extractions.ExtractionRequests.TickHistoryTimeAndSalesExtractionRequest",
    ContentFieldNames = list(
      "Trade - Price",
      "Trade - Volume",
      "Trade - Exchange Time"
    ),
    IdentifierList = list(
      odata.type = "#ThomsonReuters.Dss.Api.Extractions.ExtractionRequests.InstrumentIdentifierList",
      InstrumentIdentifiers = list(list(
        Identifier = 'AAPL.O',
        IdentifierType = 'Ric'
      ))
    ),
    Condition = list(
      MessageTimeStampIn = "GmtUtc",
      ReportDateRangeType = "Range",
      QueryStartDate = "2017-09-29T00:00:00.000Z",
      QueryEndDate = "2017-09-29T12:00:00.000Z"
    )
  )
)
url <- "https://hosted.datascopeapi.reuters.com/RestApi/v1/Extractions/ExtractRaw"
r <- httr::POST(url,add_headers(prefer = "respond-async",Authorization = token),content_type_json(),body = b,encode = "json")
Response [https://hosted.datascopeapi.reuters.com/RestApi/v1/Extractions/ExtractRaw]
  Date: 2020-09-10 09:49
  Status: 400
  Content-Type: application/json; charset=utf-8
  Size: 176 B
This is the response, I got for running the above code. I think there is something wrong, not sure what exactly that is. Could someone please help out ?