public Connection putConnection(Connection connection) {
        return connections.put(connection.getIdentifier(), connection);
    }
An internal method for modifying the Connections in this Directory.
Returns the previous connection for the given identifier, if found.

@param connection The connection to add or update the Directory with.
@return The previous connection for the connection identifier, if found.
guacamole-ext/src/main/java/org/apache/guacamole/net/auth/simple/SimpleConnectionDirectory.java