private boolean checkDefault() {
        // The global default should never be closed.
        if (this == DEFAULT || this == INSECURE) {
            logger.debug("Refusing to close the default {}; must be closed via closeDefault()",
                         ClientFactory.class.getSimpleName());
            return true;
        }
        return false;
    }
A {@link ClientFactory} which combines all discovered {@link ClientFactory} implementations.

<h2>How are the {@link ClientFactory}s discovered?</h2>

<p>{@link DefaultClientFactory} looks up the {@link ClientFactoryProvider}s available in the current JVM
using Java SPI (Service Provider Interface). The {@link ClientFactoryProvider} implementations will create
the {@link ClientFactory} implementations.
core/src/main/java/com/linecorp/armeria/client/DefaultClientFactory.java