ninja-forms-webhooks-header.php

<?php
/*
Plugin Name: Ninja Forms - Content Type Header
*/

add_filter( 'nf_remote_post_args', 'nf_add_content_type_headers' );

function nf_add_content_type_headers( $args ){

    $headers = array(
        'headers' => array(
            'Content-Type' => 'application/json'
        )
    );

    $args = array_merge( $args, $headers );

    return $args;

}

Hi dear, how include this in ninjaform webhook?
I try with custom plugin but i have this error:```

> Ooops! This add-on is not yet compatible with Ninja Forms THREE. To know more.
> 
> Ninja-forms-webhooks-header / ninja-forms-webhooks-header.php has been deactivated.