ExtensionRegistry { List<Extension> getExtensions() { if(extensions == null) { setExtensions(); } return Collections.unmodifiableList(extensions); }    }
@Test public void testValidExtensionRegistry() { ExtensionRegistry extensionRegistry = new ExtensionRegistry(); List<Extension> extensions = extensionRegistry.getExtensions(); Assert.assertNotNull(extensions); Assert.assertEquals(extensions.size(), 1); Assert.assertTrue(extensions.get(0) instanceof ButterflySpringBootExtension); }