@JsonIgnore
    public Optional<DocPath> getParent() {
        if (parentParts.isEmpty()) {
            return Optional.empty();
        } else {
            return Optional.of(new DocPath(parentParts));
        }
    }
@return The parent part name from a doc path, i.e. "Farm" from "Animals/Farm/Horse".
Throws a {@link RuntimeException} if the path is empty or there is no parent.
stroom-util-shared/src/main/java/stroom/util/shared/DocPath.java