body: RequestBody?,
    ): Builder =
      apply {
        require(method.isNotEmpty()) {
          "method.isEmpty() == true"
        }
        if (body == null) {
          require(!HttpMethod.requiresRequestBody(method)) {
            "method $method must have a request body."
          }
        } else {
          require(HttpMethod.permitsRequestBody(method)) {
            "method $method must not have a request body."