Fehler gefunden, der Preis gehört in doppelte Arrays:
$d = array( "active"=\> true, "stock"=\> 100, "taxId"=\> "0214fcd221484b7b94e3c1f6537afd5a", "price"=\> [**[**"currencyId"=\> "b7d2554b0ce847cd82f3ac9bd1c0dfca", "net"=\> 1, "linked"=\> true, "gross"=\> 1.07 **]**], "productNumber"=\> "8888", "name"=\> "TTTTTTTTTTTTTTTTTTTTTTTTTTTTT", "id"=\> $this-\>getUUID(), "createdAt"=\> null, "readOnly"=\> true,