@Nullable
    default Long defaultWriteTimeoutMillis() {
        return null;
    }
Returns the default client-side timeout of a socket write attempt in milliseconds.
Note that this flag has no effect if a user specified the value explicitly via
{@link ClientBuilder#writeTimeout(Duration)}.

<p>The default value of this flag is {@value DefaultFlagsProvider#DEFAULT_WRITE_TIMEOUT_MILLIS}.
Specify the {@code -Dcom.linecorp.armeria.defaultWriteTimeoutMillis=<integer>} JVM option to override
the default value. {@code 0} disables the timeout.
core/src/main/java/com/linecorp/armeria/common/FlagsProvider.java