Basic Substitution in SendGrid Dynamic Template

I am using the latest Java API to set dynamic template data into my SendGrid Email Templates. However though i am passing the values correctly ( i am able to see the sent dynamic values in the web dashboard), yet the value is not getting 'expressed' when the mail is being generated.

I tried with both HTML editor as well as Code editor , following the steps in the documentation . Java code is as below.

    personalization0.addTo(new Email("ron@xxxxx", "Ron Abraham"));
    personalization0.addDynamicTemplateData("otpvalue", "123456");
    mail.addPersonalization(personalization0);
    mail.setTemplateId("<templateid>");

HTML Code in SendGrid web editor

<span style="color: #000; font-size: 18px">OTP Value : {{ otpvalue }} </span></div>

In the web dashboard , when i check the sent mail i see otpvalue is being passed to the template.

I guess there is somethign missing in the way the value gets written into the HTML Dynamic Template . Any pointers ?

EDIT - Pasting the full method code below

    @PostMapping("/sendDynamicMail")
@PreAuthorize("#oauth2.hasScope('signup')")
public Response sendDynamicMailviaSendGridApi() throws IOException{

    String API_KEY = "SG.**********";
    
    Email from = new Email("*****@*****.com");
    String subject = "Test Dynamic Mail from Development team";
    Email to = new Email("ron@*****.com");

    Content content = new Content("text/html","Replace Body Content with Dynamic Template");
    
    Mail mail = new Mail(from,subject,to,content);
    mail.setReplyTo(from);
    Personalization personalization0 = new Personalization();
    
    personalization0.addTo(new Email("ron+1@*****", "Ron Abraham"));
    personalization0.addDynamicTemplateData("otpvalue", "666666");
    

    mail.addPersonalization(personalization0);
    
    //design first one template
    mail.setTemplateId("d-6dc6223eebfc49b7b887cac1c0f34fa2");
    
    
    SendGrid  sg = new SendGrid(API_KEY);
    
    Request request = new Request();
    Response response;
    
    try {
        
        request.setMethod(Method.POST);
        request.setEndpoint("mail/send");
        request.setBody(mail.build());
        response = sg.api(request);
          System.out.println(response.getStatusCode());
          System.out.println(response.getBody());
          System.out.println(response.getHeaders());
          
          return response;
    }
    catch(IOException io) {
        throw io;
    }
    finally {
        //do nothing
    }
}

Here is how the HTML Dynamic Template Looks . I have tried using the otp value in several places.

<div style="font-family: inherit; text-align: center"> <span style="color: #000; font-size: 18px">OTP Value1 : {{ otpvalue }} </span></div>

the issue was how the personalization data was being passed. personalization0.addDynamicTemplateData("dynamic_template_data", "{otpvalue:454545}" ); earlier i was passing the otp value directly as as key value pair. On analyzing the format which was being sent via curl , i made the change in java and it has worked.