private static IDelegateFactory getLoggerFactory() {
        if (!LOGGER_RESOLVED) {
            synchronized (ApimanLoggerFactory.class) {
                if (!LOGGER_RESOLVED) {
                    LOGGER_FACTORY = resolveLoggerFactory();
                    LOGGER_RESOLVED = true;
                }
            }
        }
        return LOGGER_FACTORY;
    }
Using safe DCL, resolve or get the logger factory.
common/logging/core/src/main/java/io/apiman/common/logging/ApimanLoggerFactory.java