TicketUpdate.ps1

$user = "John.Doe"
$pass = "VerySecret"
$uri  = "https://FQDNotrs/nph-genericinterface.pl/Webservice/GenericTicketConnectorREST"

$headers = @{}
$headers.Add("Accept", "application/json")
$headers.Add("Content-Type", "application/json")

# Parameter see https://github.com/znuny/Znuny/blob/dev/Kernel/GenericInterface/Operation/Ticket/TicketUpdate.pm#L68
$UpdateData = @{
	UserLogin = $user
	Password  = $pass
  Ticket = @(
    Queue = "Datacenter::2nd Level"
  )
	DynamicField = @(
		@{
			Name = "Field1"
			Value = "Value1"
		},
		@{
			Name = "Field2"
			Value = "Value2"
		}
	)
}

$json = $UpdateData | ConvertTo-Json
$Result = Invoke-RestMethod -Method PATCH -Headers $Headers -ContentType 'application/json' -Uri "$uri/Ticket/1" -Body $json
Write-Host Update ticket $Result.TicketNumber