default DependencyInjector orElse(DependencyInjector dependencyInjector) {
        requireNonNull(dependencyInjector, "dependencyInjector");
        return new OrElseDependencyInjector(this, dependencyInjector);
    }
Returns a new {@link DependencyInjector} that tries {@link #getInstance(Class)} of
this {@link DependencyInjector} first and the specified {@link DependencyInjector}.
core/src/main/java/com/linecorp/armeria/common/DependencyInjector.java