@Test
    public void testWriteReadStringMapEmpty() throws Exception
    {
        // Setup fixture.
        final Map<String, String> input = new HashMap<>();

        // Execute system under test.
        new DefaultExternalizableUtil().writeStringMap(bus.getDataOutput(), input);
        final Map<String, String> result = new DefaultExternalizableUtil().readStringMap(bus.getDataInput());

        // Verify result.
        assertTrue(areEqualString(input, result ));
    }
Asserts that the process of writing and reading a map of Strings through the {@link DefaultExternalizableUtil}
implementation results in a value that is equal to the original input, when the map is empty.
xmppserver/src/test/java/org/jivesoftware/util/cache/DefaultExternalizableUtilTest.java