Unable to assign class properties when extending Mosquitto\Client with php 7.4

[blacktek]

Hello,
I'm porting an application from a raspberry pi3 b+ (using php 5.6) to raspberry pi4 (using php 7.4)

The same class I wrote in the past that extends Mosquitto\Client is not working anymore.

My system is configured like this:

$ php --ri mosquitto

mosquitto

Mosquitto support => enabled
Compiled as dynamic module
libmosquitto version => 2.0.11
Extension version => 0.4.0

$ php -v
PHP 7.4.25 (cli) (built: Oct 23 2021 21:53:50) ( NTS )
Copyright (c) The PHP Group
Zend Engine v3.4.0, Copyright (c) Zend Technologies
with Zend OPcache v7.4.25, Copyright (c), by Zend Technologies

$ uname -a
Linux myserver 5.10.63-v7l+ #1488 SMP Thu Nov 18 16:15:28 GMT 2021 armv7l GNU/Linux

$ dpkg -l | grep mosquitto
ii libmosquitto-dev:armhf 2.0.11-1 armhf MQTT version 5.0/3.1.1/3.1 client library, development files
ii libmosquitto1:armhf 2.0.11-1 armhf MQTT version 5.0/3.1.1/3.1 client library
ii mosquitto 2.0.11-1 armhf MQTT version 5.0/3.1.1/3.1 compatible message broker

This is a part of my class:

class MqttClient extends Mosquitto\Client {

protected $connected = false;
    
public function __construct($id = null, $cleanSession = true) {
    
    $this->x = 4; // implicit declaration of a property
    
    var_dump($this);

   var_dump($this->connected);
}

}

When I istantiate an object of the class MqttClient I get:

$ php mqtt_test.php
object(MqttClient)#3 (1) {
["x"]=>
int(4)
}
PHP Notice: Undefined property: MqttClient::$connected in /var/www/library/MqttClient.class.php on line 35

Notice: Undefined property: MqttClient::$connected in /var/www/library/MqttClient.class.php on line 35
NULL

Bassically I'm unable to access the properties of my class. If I remove "extends Mosquitto\Client" it works; the same if I try to extend any other class.

I think there is something broken with the extension; I tried to uninstall and reinstall again the package (first install was with pecl install Mosquitto-alpha - the second, after uninstall, was with pecl install Mosquitto-beta). But no change.

Of course nothing changes if I use public instead of protected properties.

If inside the constructor I put

$z1 = new ReflectionClass($this);
print_r($z1->getProperties());

I can see the properties:

Array
(
[0] => ReflectionProperty Object
(
[name] => connected
[class] => MqttClient
)

)
$

Do you have any idea? I think there is something not working with the extension. The exact same code was working with php5.6 on pi3

Thank you!