protected function createNewSendTransaction($wallet_uuid, $source_uuid, $asset, $destinations, $send_parameters)
    {
        if ($send_parameters === null) {
            $send_parameters = [];
        }

        if (!isset($send_parameters['requestId'])) {
            $send_parameters['requestId'] = Uuid::uuid4()->toString();
        }
        if (!isset($send_parameters['feeRate'])) {
            $send_parameters['feeRate'] = 'medium';
        }

        $post_vars = array_merge([
            'sourceId' => $source_uuid,
            'asset' => $asset,
            'destinations' => $destinations,
        ], $send_parameters);

        $api_result = $this->newAPIRequest('POST', $wallet_uuid . '/sends', $post_vars);
        return $this->processSendAPICallResult($api_result);
    }