void () { @SuppressWarnings("rawtypes") ExtensionPoint extensionPoint = buildExtensionPoint(Integer.class); try { extensionPoint.registerExtension((double)0, disposable); fail("must throw"); } catch (RuntimeException ignored) { } assertThat(extensionPoint.getExtensionList()).isEmpty(); extensionPoint.registerExtension(0, disposable); assertThat(extensionPoint.getExtensionList()).hasSize(1); }