ForTatu.java

    @Test
    public void testBetterErrorMessage() throws Exception
    {
        ObjectMapper mapper = new ObjectMapper();
        try {
            mapper.writeValueAsString(new Thing());
            fail("should have raised an exception against a private class");
        }
        catch (Exception e) {
            assertThat(e.getMessage(), containsString("private"));
        }
    }

    private static class Thing
    {
        @JsonAnyGetter
        public Map getProperties()
        {
            HashMap map = new HashMap();
            map.put("a", "A");
            return map;
        }
    }