item.timestamp = ZonedDateTime.ofInstant(Instant.ofEpochMilli(timestamp), Clock.systemDefaultZone().getZone());
        return item;
    }

    /**
     * Returns the updated source map by merging with existing source.
     * @param existingSource The existing source map.
     * @return The updated source map.
     */
    public Map<String, Object> getUpdatedSource(final Map<String, Object> existingSource) {