source.put("zero", 0);
        source.put("negativeDouble", -1.5);

        final String json = new JsonIndexExportFormatter().format(source, Collections.emptySet());

        assertTrue(json.contains("\"negative\": -42"));
        assertTrue(json.contains("\"zero\": 0"));
        assertTrue(json.contains("\"negativeDouble\": -1.5"));
    }

    @Test