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

        // Create collection with enough backing space to contain one
        // connection per identifier given
        Collection<Connection> matchingConnections =
                new ArrayList<Connection>(identifiers.size());

        // Add all connnections which exist according to get()
        for (String identifier : identifiers) {
            Connection connection = get(identifier);
            if (connection != null)
                matchingConnections.add(connection);
        }

        return Collections.unmodifiableCollection(matchingConnections);

    }
Registers a new share key such that the connection associated with that
share key is accessible through this directory. The share key will be
automatically de-registered when it is no longer valid.

@param shareKey
    The share key to register.
extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-base/src/main/java/org/apache/guacamole/auth/jdbc/sharing/connection/SharedConnectionDirectory.java