@Override
    public String toString() {
        return "Word{" +
                "word='" + word + '\'' +
                ", sourceUuid='" + sourceUuid + '\'' +
                ", additionalSourceUuids=" + additionalSourceUuids +
                '}';
    }
@return The list of other source documents that contain this word. This will only
contain items if the word list has been de-duplicated.
stroom-core-shared/src/main/java/stroom/dictionary/shared/Word.java