public PropertyPath merge(final String otherPart) {
        if (otherPart == null || otherPart.isEmpty()) {
            return this;
        } else {
            return new PropertyPath(this.getParts(), otherPart);
        }
    }
Merge part onto the end of this and return a new {@link PropertyPath}
stroom-util-shared/src/main/java/stroom/util/shared/PropertyPath.java