curl --request PUT \
  --url https://cpaas.zoho.com/v1.1/mailagents/{mailagent-alias}/templates/{template-key} \
  --header 'Authorization: Zoho-oauthtoken d92d4xxxxxxxxxxxxx15f52' \
  --header 'content-type: application/json' \
  --data '{"htmlbody":"<h1> Hi User </h1>, Welcome aboard","template_name":"E-invite","subject":"Invitation to the event"}'

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.io.IOException;
import java.net.http.HttpTimeoutException;

public class Main {
  public static void main(String[] args) {

    HttpRequest request = HttpRequest.newBuilder()
        .uri(URI.create("https://cpaas.zoho.com/v1.1/mailagents/{mailagent-alias}/templates/{template-key}"))
        .header("content-type", "application/json")
        .header("Authorization", "Zoho-oauthtoken d92d4xxxxxxxxxxxxx15f52")
        .method("PUT", HttpRequest.BodyPublishers.ofString("{\"htmlbody\":\"
 Hi User 
, Welcome aboard\",\"template_name\":\"E-invite\",\"subject\":\"Invitation to the event\"}"))
        .build();
    HttpResponse response = HttpClient.newHttpClient().send(request, HttpResponse.BodyHandlers.ofString());
    System.out.println(response.body());
  
  }
}
    

import http.client

conn = http.client.HTTPSConnection("cpaas.zoho.com")

payload = "{\"htmlbody\":\"
 Hi User 
, Welcome aboard\",\"template_name\":\"E-invite\",\"subject\":\"Invitation to the event\"}"

headers = {
    'content-type': "application/json",
    'Authorization': "Zoho-oauthtoken d92d4xxxxxxxxxxxxx15f52"
    }

conn.request("PUT", "/v1.1/mailagents/{mailagent-alias}/templates/{template-key}", payload, headers)

res = conn.getresponse()
data = res.read()

print(data.decode("utf-8"))

    headersMap = Map();
    headersMap.put("Content-Type", "application/json");
    headersMap.put("Accept", "application/json");

    data=Map();
    data.put("htmlbody","
 Hi User 
, Welcome aboard");
    data.put("template_name","E-invite");
    data.put("subject","Invitation to the event");

    response = invokeUrl
    [
        url: "https://cpaas.zoho.com/v1.1/mailagents/{mailagent-alias}/templates/{template-key}"
        type: PUT
        headers: headersMap
        body: data
        connection: connection_name
    ]

    info response;