curl --request POST \
  --url http://{host}:{port}/{contextPath}/task/{id}/attachment/create \
  --header 'Authorization: Basic <encoded-value>' \
  --header 'Content-Type: multipart/form-data' \
  --data-binary $'------------------------------925df49a954b\n                        Content-Disposition: form-data; name="url"\n\n                        http://my-attachment-content-url.de\n                        ------------------------------925df49a954b\n                        Content-Disposition: form-data; name="attachment-name"\n\n                        attachmentName\n                        ------------------------------925df49a954b\n                        Content-Disposition: form-data; name="attachment-description"\n\n                        attachmentDescription\n                        ------------------------------925df49a954b\n                        Content-Disposition: form-data; name="attachment-type"\n\n                        attachmentType\n                        ------------------------------925df49a954b--'

import requests

url = "http://{host}:{port}/{contextPath}/task/{id}/attachment/create"

headers = {
    "Authorization": "Basic <encoded-value>",
    "Content-Type": "multipart/form-data"
}

response = requests.post(url, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Basic <encoded-value>', 'Content-Type': 'multipart/form-data'}
};

fetch('http://{host}:{port}/{contextPath}/task/{id}/attachment/create', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_PORT => "62437",
  CURLOPT_URL => "http://{host}:{port}/{contextPath}/task/{id}/attachment/create",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => "------------------------------925df49a954b\n                        Content-Disposition: form-data; name=\"url\"\n\n                        http://my-attachment-content-url.de\n                        ------------------------------925df49a954b\n                        Content-Disposition: form-data; name=\"attachment-name\"\n\n                        attachmentName\n                        ------------------------------925df49a954b\n                        Content-Disposition: form-data; name=\"attachment-description\"\n\n                        attachmentDescription\n                        ------------------------------925df49a954b\n                        Content-Disposition: form-data; name=\"attachment-type\"\n\n                        attachmentType\n                        ------------------------------925df49a954b--",
  CURLOPT_HTTPHEADER => [
    "Authorization: Basic <encoded-value>",
    "Content-Type: multipart/form-data"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "http://{host}:{port}/{contextPath}/task/{id}/attachment/create"

	payload := strings.NewReader("------------------------------925df49a954b\n                        Content-Disposition: form-data; name=\"url\"\n\n                        http://my-attachment-content-url.de\n                        ------------------------------925df49a954b\n                        Content-Disposition: form-data; name=\"attachment-name\"\n\n                        attachmentName\n                        ------------------------------925df49a954b\n                        Content-Disposition: form-data; name=\"attachment-description\"\n\n                        attachmentDescription\n                        ------------------------------925df49a954b\n                        Content-Disposition: form-data; name=\"attachment-type\"\n\n                        attachmentType\n                        ------------------------------925df49a954b--")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Basic <encoded-value>")
	req.Header.Add("Content-Type", "multipart/form-data")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("http://{host}:{port}/{contextPath}/task/{id}/attachment/create")
  .header("Authorization", "Basic <encoded-value>")
  .header("Content-Type", "multipart/form-data")
  .body("------------------------------925df49a954b\n                        Content-Disposition: form-data; name=\"url\"\n\n                        http://my-attachment-content-url.de\n                        ------------------------------925df49a954b\n                        Content-Disposition: form-data; name=\"attachment-name\"\n\n                        attachmentName\n                        ------------------------------925df49a954b\n                        Content-Disposition: form-data; name=\"attachment-description\"\n\n                        attachmentDescription\n                        ------------------------------925df49a954b\n                        Content-Disposition: form-data; name=\"attachment-type\"\n\n                        attachmentType\n                        ------------------------------925df49a954b--")
  .asString();

require 'uri'
require 'net/http'

url = URI("http://{host}:{port}/{contextPath}/task/{id}/attachment/create")

http = Net::HTTP.new(url.host, url.port)

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Basic <encoded-value>'
request["Content-Type"] = 'multipart/form-data'
request.body = "------------------------------925df49a954b\n                        Content-Disposition: form-data; name=\"url\"\n\n                        http://my-attachment-content-url.de\n                        ------------------------------925df49a954b\n                        Content-Disposition: form-data; name=\"attachment-name\"\n\n                        attachmentName\n                        ------------------------------925df49a954b\n                        Content-Disposition: form-data; name=\"attachment-description\"\n\n                        attachmentDescription\n                        ------------------------------925df49a954b\n                        Content-Disposition: form-data; name=\"attachment-type\"\n\n                        attachmentType\n                        ------------------------------925df49a954b--"

response = http.request(request)
puts response.read_body

{
  "id": "attachmentId",
  "name": "attachmentName",
  "taskId": "aTaskId",
  "description": "attachmentDescription",
  "type": "attachmentType",
  "url": "http://my-attachment-content-url.de",
  "createTime": "2017-02-10T14:33:19.000+0200",
  "removalTime": "2018-02-10T14:33:19.000+0200",
  "rootProcessInstanceId": "aRootProcessInstanceId",
  "links": [
    {
      "method": "GET",
      "href": "http://localhost:38080/rest-test/task/aTaskId/attachment/aTaskAttachmentId",
      "rel": "self"
    }
  ]
}

{
  "type": "<string>",
  "message": "<string>",
  "code": 123
}

{
  "userId": "<string>",
  "missingAuthorizations": [
    {
      "permissionName": "<string>",
      "resourceName": "<string>",
      "resourceId": "<string>"
    }
  ],
  "type": "<string>",
  "message": "<string>",
  "code": 123
}