// Test null version
        NullSearchLogEvent nullEvent = new NullSearchLogEvent();
        assertNull(nullEvent.getVersionNo());

        // Test zero version
        EmptySearchLogEvent emptyEvent = new EmptySearchLogEvent();
        assertEquals(Long.valueOf(0L), emptyEvent.getVersionNo());

        // Test negative version
        event.setVersionNo(-1L);

    }

    @Override
    public String getId() {
        return asDocMeta().id();
    }

    public void setId(final String id) {
        asDocMeta().id(id);
    }

    public Long getVersionNo() {
        return asDocMeta().version();
    }

    public void setVersionNo(final Long version) {
        asDocMeta().version(version);
    }

    @Override
    public String toString() {

    }

    @Override
    public String getId() {
        return asDocMeta().id();
    }

    public void setId(final String id) {
        asDocMeta().id(id);
    }

    public Long getVersionNo() {
        return asDocMeta().version();
    }

    public void setVersionNo(final Long version) {
        asDocMeta().version(version);
    }

    @Override
    public String toString() {

    }

    @Override
    public String getId() {
        return asDocMeta().id();
    }

    public void setId(final String id) {
        asDocMeta().id(id);
    }

    public Long getVersionNo() {
        return asDocMeta().version();
    }

    public void setVersionNo(final Long version) {
        asDocMeta().version(version);
    }

    @Override
    public Integer getTimeToLive() {

        final Map<String, Object> source = toLowerHyphen(searchLogEvent.toSource());
        source.put("_id", searchLogEvent.getId());
        // source.put("version_no", searchLogEvent.getVersionNo());
        source.put("event_type", searchLogEvent.getEventType());
        return source;
    }

    /**
     * Converts a map to lower hyphen case.
     *
     * @param source The source map.