@Test
    public void nemesisAddressesAreValid() {
      // Arrange:
      final Block block = this.loadNemesisBlock();

      // Act:
      final Set<Address> allAddresses =
          block
              .getTransactions()
              .stream()
              .flatMap(t -> t.getAccounts().stream().map(Account::getAddress))
              .collect(Collectors.toSet());

      // Assert:
      for (final Address address : allAddresses) {
        Assert.assertThat(address.toString(), address.isValid(), IsEqual.equalTo(true));
      }
    }