### Question:
BlockExplorers { public static BlockExplorer getDefaultBlockExplorer() { return new BlockChainInfoBlockExplorer(); } private  BlockExplorers(); static List<BlockExplorer> getAll(); static Optional<BlockExplorer> getBlockExplorerById(String id); static BlockExplorer getDefaultBlockExplorer();  }### Answer:
@Test public void testDefaultBlockExplorer() { BlockExplorer defaultBlockExplorer = BlockExplorers.getDefaultBlockExplorer(); assertThat(defaultBlockExplorer instanceof BlockChainInfoBlockExplorer).isTrue(); }