in src/main/java/org/apache/commons/logging/LogFactory.java [894:905]
private static void cacheFactory(final ClassLoader classLoader, final LogFactory factory) {
// Ideally we would assert(factory != null) here. However reporting
// errors from within a logging implementation is a little tricky!
if (factory != null) {
if (classLoader == null) {
nullClassLoaderFactory = factory;
} else {
factories.put(classLoader, factory);
}
}
}