Making omnisendApi protected to let the class being subclassable

[massimoconti]

In my use case I would like to subclass \Omnisend and redefine \Omnisend::omnisendApi so I might able to add logging functionality in a single place like this:

class LoggableOmnisend extends \Omnisend
{
    protected $logger;

    protected function omnisendApi($endpoint, $method = "POST", $fields = array(), $queryParams = array())
    {
        $response = parent::omnisendApi($endpoint, $method, $fields, $queryParams);

        if ($this->logger) {
            $this->logger->debug("Ominisend $method $endpoint", [
                'fields' => $fields,
                'query' => $queryParams,
                'response' => $response,
                'error' => $this->lastError(),
            ]);
        }

        return $response;
    }
}

[massimoconti]

Fixed properties modifiers.