@Override
    public DefaultServiceConfigSetters blockingTaskExecutor(int numThreads) {
        checkArgument(numThreads >= 0, "numThreads: %s (expected: >= 0)", numThreads);
        final BlockingTaskExecutor executor = BlockingTaskExecutor.builder()
                                                                  .numThreads(numThreads)
                                                                  .build();
        return blockingTaskExecutor(executor, true);
    }
A default implementation of {@link ServiceConfigSetters} that stores service related settings
and provides a method {@link DefaultServiceConfigSetters#toServiceConfigBuilder(Route, String, HttpService)}
to build {@link ServiceConfigBuilder}.
core/src/main/java/com/linecorp/armeria/server/DefaultServiceConfigSetters.java