ninja-core/src/main/java/ninja/standalone/StandaloneHelper.java
static public Class<? extends Standalone> resolveStandaloneClass() {
        return resolveStandaloneClass(
            System.getProperty(Standalone.KEY_NINJA_STANDALONE_CLASS),
            ForwardingServiceLoader.loadWithSystemServiceLoader(Standalone.class),
            Standalone.DEFAULT_STANDALONE_CLASS
        );
    }
static public Class<? extends Standalone> resolveStandaloneClass() {
        return resolveStandaloneClass(
            System.getProperty(Standalone.KEY_NINJA_STANDALONE_CLASS),
            ForwardingServiceLoader.loadWithSystemServiceLoader(Standalone.class),
            Standalone.DEFAULT_STANDALONE_CLASS
        );
    }
Resolves which standalone class to use. Either defined as a system
property or falling back to the default.
@return The resolved standalone class to use