App\Entity\User.php

<?php

// ...

use Symfony\Component\Serializer\Annotation\Groups;

/**
 * @ApiResource(
 *     normalizationContext={"groups"={"userList"}},
 *     denormalizationContext={"groups"={"userCreate"}}
 * )
 * ...
 */
class User implements UserInterface
{
    /**
     * ...
     * @Groups({"userList"})
     */
    private $id;

    /**
     * ...
     * @Groups({"userList", "userCreate"})
     */
    public $name;

    /**
     * ...
     * @Groups({"userCreate"})
     */
    public $plainPassword;

   // ...
}