Installing/Enabling Custom Webform Hander I am very new to Drupal development though I am an experienced developer.  I created a custom Webform Handler following these tutorials and postings:
These for what files to create and where:
Create a custom webform handler in Drupal 8
Create a Webform Handler that sends a notification to Slack
Add a custom submission handler to a form
This post for the code to redirect a user to another webform upon form submission:
Page redirect in custom WebformHandlerBase
I have looked at everything and everything looks correct.  Here's what's in the YAML file modules\custom\redirect_to_ccbilling\redirect_to_ccbilling.info.yml:
name: 'Redirect to CC Billing'
description: 'Provides a custom webform handler for the &quot;submit an event&quot; webform so it will redirect to another webform node'
core_version_requirement: ^8.8
Core: 8.x
package: Custom
type: module

Here's what's in the modules\custom\redirect_to_ccbilling\src\Plugin\WebformHandler\RedirectToCCBillingWebformHandler.php:
&lt;?php
namespace Drupal\redirect_to_ccbilling\Plugin\WebformHandler;

use Drupal\Core\Session\AccountInterface;
use Drupal\Core\Serialization\Yaml;
use Drupal\Core\Form\FormStateInterface;
use Drupal\webform\Plugin\WebformHandlerBase;
use Drupal\webform\src\WebformSubmissionInterface;

/**
 * Form submission handler.
 *
 * @RedirectToCCBilling(
 *   id = &quot;Redirect to CC Billing&quot;,
 *   label = @Translation(&quot;Redirect to CC Billing&quot;),
 *   category = @Translation(&quot;Webform Handler&quot;),
 *   description = @Translation(&quot;Redirect user to the credit card billing page.&quot;),
 *   cardinality = 
 *       \Drupal\webform\Plugin\WebformHandlerInterface::CARDINALITY_SINGLE,
 *   results = 
 *    \Drupal\webform\Plugin\WebformHandlerInterface::RESULTS_PROCESSED,
 * )
 */

 class RedirectToCCBillingWebformHandler extends WebformHandlerBase {
 /**
  * {@inheritdoc}
  */
    public function submitForm(array &amp;$form, FormStateInterface $form_state, WebformSubmissionInterface $webform_submission) {

       $form_id = 'webform_submission_' . $webform_submission-&gt;getWebform()-&gt;id() . '_form';
       if($form_id == 'webform_submission_xxx_form') {
         $values = $webform_submission-&gt;getData();  
         /* Take the action based on the Webform submission values */   
       }    
    }

    public function confirmForm(array &amp;$form, FormStateInterface $form_state, WebformSubmissionInterface $webform_submission) {
       $form_id = 'webform_submission_' . $webform_submission-&gt;getWebform()-&gt;id() . '_form';
       if($form_id == 'webform_submission_xxx_form')
       {
          if(based_on_some_condition) {
          /* Here 12 is the node id where i wanted to redirect to */
          $form_state-&gt;setRedirect('entity.node.canonical',['node' =&gt; 1764]);
       }
    }
}   
?&gt;

I went into the Extend menu and under Custom section I selected the Redirect to CC Billing module/handler and clicked Install at the bottom of the page.  However, when I go back to my webform &gt;&gt; setting &gt;&gt; emails / handlers &gt;&gt; +add handler all I see is this:

I don't know what I am missing for my custom handler to not be appearing in the list of handlers.
A few things in addition to what @4k4 commented:

Please replace your annotation plugin reference with @WebformHandler

Use lower case / snake case names for your Webform Handler ID eg. redirect_to_ccbilling

Ensure correct directory structure where the plugin discovery will look for Webform Handler classes. This should be /modules/custom/redirect_to_ccbilling/src/Plugin/WebformHandler/RedirectToCCBillingWebformHandler.php

Ensure that your module is enabled. Either via drush en redirect_to_ccbilling -y or by enabling it on the Extend module page.


/**
 * Form submission handler.
 *
 * @WebformHandler(
 *   id = &quot;redirect_to_ccbilling&quot;,
 *   label = @Translation(&quot;Redirect to CC Billing&quot;),
 *   category = @Translation(&quot;Webform Handler&quot;),
 *   description = @Translation(&quot;Redirect user to the credit card billing page.&quot;),
 *   cardinality = \Drupal\webform\Plugin\WebformHandlerInterface::CARDINALITY_SINGLE,
 *   results = \Drupal\webform\Plugin\WebformHandlerInterface::RESULTS_PROCESSED,
 * )
 */
class RedirectToCCBillingWebformHandler extends WebformHandlerBase {