public ClientFactoryBuilder connectionPoolListener(ConnectionPoolListener connectionPoolListener) {
        return connectionPoolListener(connectionPoolListener, true);
    }
Sets the listener which is notified on a connection pool event.
Note that the specified {@link ConnectionPoolListener} will be closed automatically when the
{@link ClientFactory} is closed.
core/src/main/java/com/linecorp/armeria/client/ClientFactoryBuilder.java