private Map<String, ClassEntity> loadExtensionClass() {
        SPI annotation = clazz.getAnnotation(SPI.class);
        if (Objects.nonNull(annotation)) {
            String value = annotation.value();
            if (StringUtils.isNotBlank(value)) {
                cachedDefaultName = value;
            }
        }
        Map<String, ClassEntity> classes = new HashMap<>(16);
        loadDirectory(classes);
        return classes;
    }
Gets extension classes.

@return the extension classes
shenyu-spi/src/main/java/org/apache/shenyu/spi/ExtensionLoader.java