public void valid(String extensionName) {
        if (!inputExtensions.map().containsKey(extensionName))
            throw new IllegalArgumentException(String.format("Extension %s was not found in the original extensions", extensionName));
        validatedExtensions.put(extensionName, inputExtensions.map().get(extensionName));
    }
@Test
    public void testCannotValidateExtensionWhichWasNotGiven() {
        Map<String, String> extensions = new HashMap<>();
        extensions.put("hello", "bye");

        OAuthBearerExtensionsValidatorCallback callback = new OAuthBearerExtensionsValidatorCallback(TOKEN, new SaslExtensions(extensions));

        assertThrows(IllegalArgumentException.class, () -> callback.valid("???"));
    }