curl --request GET \
  --url http://{host}:{port}/{contextPath}/history/activity-instance/{id} \
  --header 'Authorization: Basic <encoded-value>'

import requests

url = "http://{host}:{port}/{contextPath}/history/activity-instance/{id}"

headers = {"Authorization": "Basic <encoded-value>"}

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

print(response.text)

const options = {method: 'GET', headers: {Authorization: 'Basic <encoded-value>'}};

fetch('http://{host}:{port}/{contextPath}/history/activity-instance/{id}', 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}/history/activity-instance/{id}",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "GET",
  CURLOPT_HTTPHEADER => [
    "Authorization: Basic <encoded-value>"
  ],
]);

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

curl_close($curl);

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

package main

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

func main() {

	url := "http://{host}:{port}/{contextPath}/history/activity-instance/{id}"

	req, _ := http.NewRequest("GET", url, nil)

	req.Header.Add("Authorization", "Basic <encoded-value>")

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

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

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.get("http://{host}:{port}/{contextPath}/history/activity-instance/{id}")
  .header("Authorization", "Basic <encoded-value>")
  .asString();

require 'uri'
require 'net/http'

url = URI("http://{host}:{port}/{contextPath}/history/activity-instance/{id}")

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

request = Net::HTTP::Get.new(url)
request["Authorization"] = 'Basic <encoded-value>'

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

{
  "id": "aActivityInstId",
  "activityId": "anActivity",
  "activityName": "anActivityName",
  "activityType": "userTask",
  "assignee": "peter",
  "calledProcessInstanceId": "aHistoricCalledProcessInstanceId",
  "calledCaseInstanceId": null,
  "canceled": true,
  "completeScope": false,
  "durationInMillis": 2000,
  "endTime": "2013-04-23T18:42:43.000+0200",
  "executionId": "anExecutionId",
  "parentActivityInstanceId": "aHistoricParentActivityInstanceId",
  "processDefinitionId": "aProcDefId",
  "processInstanceId": "aProcInstId",
  "startTime": "2013-04-23T11:20:43.000+0200",
  "taskId": "aTaskId",
  "tenantId": null,
  "removalTime": "2018-02-10T14:33:19.000+0200",
  "rootProcessInstanceId": "aRootProcessInstanceId"
}

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