How can I display elements of my ArrayCollection working with joined Tables and ManyToMany relations?

In my entity documents I have a field called linkedDocuments:

class Documents {

  /**
  * @ORM\ManyToMany(targetEntity="App\Entity\Documents")
  * @ORM\JoinTable(name="documents_documents",
  *      joinColumns={@JoinColumn(name="link_origin", referencedColumnName="id")},
  *      inverseJoinColumns={@JoinColumn(name="link_destination", referencedColumnName="id")}
  *      )
  * @Groups("documents")
  */
  private $linkedDocuments;


  public function __construct() {
    $this->linkedDocuments = new ArrayCollection();
  }

In my controller I create an object:

$table = $this->em->getRepository(Documents::class)->findAll();

This is the output:

array:1 [▼
  0 => Documents^ {#6414 ▼
    -id: 1
    -linkedDocuments: PersistentCollection^ {#5724 ▼
      -snapshot: []
      -owner: Documents^ {#6414}
      -association: array:19 [ …19]
      -em: EntityManager^ {#2786 …11}
      -backRefFieldName: null
      -typeClass: ClassMetadata {#2613 …}
      -isDirty: false
      #collection: ArrayCollection^ {#2820 ▼
        -elements: []
      }
      #initialized: true
    }
  }
]

My Array Collection is empty. But I expect it to have two elements, because I see them in my mySQL database. Like this:

 -elements: array:2 [▼
          0 => linkedDocuments^ {#1204 ▶}
          1 => linkedDocuments ▶}
        ]

I found a solution. Instead of this:

$table = $this->em->getRepository(Documents::class)->findAll();

I had to write this:

$table = $this->em->getRepository(Documents::class)->linkedDocuments($id);

And in my DocumentsRepository I added the function:

  public function linkedDocuments($id)
    {
      return $this->createQueryBuilder('d')
      ->leftJoin('d.linkedDocuments', 'dd')
      ->where('d.id = :id')
      ->setParameter(':id', $id)
      ->getQuery()
      ->execute();
    }