* a performance enhancement. The client does not have to filter
 * the names and the server does not have to return all directory
 * entries.
 * <p>
 * The wildcard expression may consist of two special meta
 * characters in addition to the normal filename characters. The '*'
 * character matches any number of characters in part of a name. If
 * the expression begins with one or more '?'s then exactly that