[Copilot]

The "Static Analyse" CI job fails because PHPStan's strict-assertion rule flags assertEmpty() ("assertEmpty() is not allowed. Use more strict assertion."). Two tests used it.

• InAppPurchasesControllerTest: assertEmpty($content) becomes assertSame([], $content). validateResponse() returns the JSON-decoded body as an array, so an empty response decodes to [].
• LicenseControllerTest: assertEmpty($response->getContent()) becomes assertSame('', $response->getContent()). The 204 response should have an empty string body.

// before
static::assertEmpty($response->getContent());
// after
static::assertSame('', $response->getContent());

I haven't run PHPStan or the tests yet. The [] expectation in InAppPurchasesControllerTest is unconfirmed, so a reviewer should check that test passes.