public ClientFactoryBuilder http2GracefulShutdownTimeoutMillis(long http2GracefulShutdownTimeoutMillis) {
        checkArgument(http2GracefulShutdownTimeoutMillis >= 0,
                      "http2GracefulShutdownTimeoutMillis: %s (expected: >= 0)",
                      http2GracefulShutdownTimeoutMillis);
        option(ClientFactoryOptions.HTTP2_GRACEFUL_SHUTDOWN_TIMEOUT_MILLIS,
               http2GracefulShutdownTimeoutMillis);
        return this;
    }
Sets the graceful connection shutdown timeout in milliseconds.
{@code 0} disables the timeout and closes the connection immediately after sending a GOAWAY frame.
core/src/main/java/com/linecorp/armeria/client/ClientFactoryBuilder.java