@Override
    public Collection<ObjectType> getAll(Collection<String> identifiers)
            throws GuacamoleException {

        // Reduce requested identifiers to only those which occur within the
        // originally-specified subset
        identifiers = new ArrayList<String>(identifiers);
        identifiers.retainAll(this.identifiers);

        // Delegate to underlying directory
        return directory.getAll(identifiers);

    }
Creates a new DirectoryView which provides access to a read-only subset
of the objects in the given Directory. Only objects whose identifiers
are within the provided set will be accessible.

@param directory
    The Directory of which this DirectoryView represents a subset.

@param identifiers
    The identifiers of all objects which should be accessible through
    this DirectoryView. Objects which do not have identifiers within
    the provided set will be inaccessible.
guacamole/src/main/java/org/apache/guacamole/rest/directory/DirectoryView.java