post("/post/users") {
                val received = call.receive<List<User>>()
                println(received)
                println(received::class)
                println(received[0]::class)
                assertEquals(usersList, received)
                call.respond(received)
            }

prints:

[[io.ktor.client.features.json.test.JsonTest.User, {name=vasya, age=10}]]
class java.util.ArrayList
class java.util.ArrayList

and then fails at the assert