Symfony : How to deserialize a JSON file that contains a set of objects that have properties made of an array of objects?

Question

In Symfony, I try to deserialize a set of objects of type "Activity" from a JSON file. Every object activity contains three properties:

1. Intger Id.
2. Property of Class type "Person" called "host".
3. Array of Objects of class type "Person" called "participants".

I tried a Symfony made deserializer to deserialize objects of type Person and it worked well. But when I try to use it to deserialize an object of type Activity it gave me an error.

$serializer = new Serializer(
               [new GetSetMethodNormalizer(), new ArrayDenormalizer()],
               [new JsonEncoder()]
              );
$members = $serializer->deserialize($json, 'ActivitiesBundle\Entity\Person[]', 'json');

The other one that failed to extract data:

$activities = $serializer->deserialize($json, 
'ActivitiesBundle\Entity\Activity[]', 'json');

class Activity 
{
    private $id;
    private $host;
    private $participants = [];

public function getId()
    {
        return $this->id;
    }

public function setId($id)
    {
        $this->id = $id;

        return $this;
    }

 public function getHost() {

    return $this->host;
  }

public function setHost(Person $host) {

    $this->host = $host;

     return $this;
  }

  public function getParticipants() {

    return $this->participants;
  }

public function setParticipants(\Person ... $participants) {

    $this->participants = $participants;

    return $this;
  }
}

class Person 
{
    private $id;
    private $name;

public function getId()
    {
        return $this->id;
    }

public function setId($id)
    {
        $this->id = $id;

        return $this;
    }

 public function getName() {

    return $this->name;
  }

public function setName($name) {

    $this->name = $name;

     return $this;
  }
}

The error I get is:

Type error: Argument 1 passed to ActivitiesBundle\Entity\Activity::setHost() 
must be an instance of  ActivitiesBundle\Entity\Person

This is an extract of the JSON that contains data about activities:

[
    {
        "id": 1,
        "host": {
            "id": 48,
            "name": "Name48",
        },
        "participants": [
            {
                "id": 975,
                "name": "Name975",
            },
            {
                "id": 866,
                "name": "Name866",
            },
            {
                "id": 355,
                "name": "Name355",
            },
            {
                "id": 856,
                "name": "Name856",
            }
        ]
    },
    {
        "id": 2,
        "host": {
                    .....