Quickstart: Go

Standard library only — except uuid for the idempotency key (go get github.com/google/uuid).

package main

import (
  "bytes"
  "encoding/json"
  "fmt"
  "net/http"
  "github.com/google/uuid"
)

func main() {
  // marshal payload, POST it, check for 202 —
  // full source in the copy button above.
}

go run send.go → expect 202 Accepted. Timeouts deserve the same idempotency-key retry discipline as every other language: read why.