Legacy API key migration - PHP ISDK

@Farrukh_Naseem, if you look at Marion code you will see what he has done.

If you are using the original XML-RPC Library with the SDK then that will need upgrading.
The Newer Version of the XML-RPC Library has support for Customisable Headers.

I posted a reply to Marion in which you can use that instead of modifying the library.

I made changes to the “methodCaller” function. Here is what I changed to work with the latest XML-RPC Library.

        // * Original Way *
        // $call = $this->xmlrpc_request($service, $callArray);
        // array_unshift($call->params, $this->encKey);
 
        /* Set up the call */
        // 2023-06-05 - Fix to make it work for the PHP XML-RPC library v4.10.1 as "params" is not exposed anymore.
         $call = $this->xmlrpc_request($service, array_merge([ $this->xmlrpc_encode($this->key) ], $callArray));

        // Check the OAuth Token to see if it needs to be refreshed prior to the call.
        $headers = 
        [
            "Content-Type: text/xml",
            "Accept-Charset: UTF-8,ISO-8859-1,US-ASCII",
            "Expect:",
            "X-Keap-API-Key: {$this->key}"
        ];

         $this->client->setOption('extracurlopts', [ CURLOPT_HTTPHEADER => $headers ]);

My iSDK has been modified over the years, so it is not the same as the original one.