static boolean isValidLeafPart(final String leafPart) {
        if (leafPart != null) {
            final int len = leafPart.length();
            if (len % 3 == 0) {
                boolean isAllNumeric = true;
                for (int i = 0; i < len; i++) {
                    final char chr = leafPart.charAt(i);
                    if (!Character.isDigit(chr)) {
                        isAllNumeric = false;
                        break;
                    }
                }
                return isAllNumeric;
            } else {
                return false;
            }
        } else {
            return false;
        }
    }
@return True if the leaf part of a path is valid when viewed in isolation,
i.e. ignoring other path parts.
stroom-state/stroom-planb-impl/src/main/java/stroom/planb/impl/data/DirUtil.java