void () { ExtensionPoint<@NotNull Integer> extensionPoint = buildExtensionPoint(Integer.class); extensionPoint.registerExtension(123, disposable); Object[] extensions = extensionPoint.getExtensions(); assertThat(extensions).describedAs("One extension").hasSize(1); assertThat(extensions).isInstanceOf(Integer[].class); assertThat(extensions[0]).isEqualTo(123); }