issue fix

test.java

@SuppressWarnings("unchecked")
    private <T> T stringAsObject(String value, Class<T> targetClass, String defaultValue) {
        value = StringUtils.trimToNull(value);
        if (value == null) {
            value = defaultValue;
        }
        if (value == null || value.length() == 0) {
            return null;
        }

        value = resolve(value);

        if (targetClass == String.class) {
            return (T) value;
        }

        if (value.startsWith("$")) {
            // this is a reference name
            return aliasNameAsObject(value, targetClass, null);
        }

        if (targetClass == Object.class) {
            return aliasNameAsObject(value, targetClass, null);
        }

        if (TypeCastUtils.support(targetClass)) {
            return TypeCastUtils.convert(value, targetClass);
        }

        if (ClassUtils.available(value)) {
            // this is a class name
            return aliasNameAsObject(value, targetClass, null);
        }
      
        ClassLoader loader = getClass().getClassLoader();
        if (ClassUtils.available(value， loader)) {
            return aliasNameAsObject(value, targetClass, loader);
        }

        throw new IllegalStateException("Cannot convert to " + targetClass + " from `" + value + "`");
    }

    protected <T> T aliasNameAsObject(String aliasName, Class<T> targetClass, ClassLoader loader) {
        // 1. get class name and props
        String className;
        Set<String> propNames;

        if (aliasName.startsWith("$")) {
            // this is a reference name
            className = doGetValue(aliasName, String.class, null);
            propNames = keySet(aliasName.concat("."));
        } else {
            // this is a class name
            className = aliasName;
            propNames = null;
        }

        // 2. load class
        Class<?> cls;

        try {
            cls = ClassLoaderUtils.loadClassEx(className, loader);
        } catch (ClassNotFoundException e) {
            throw new IllegalStateException(e);
        }
        if (!targetClass.isAssignableFrom(cls)) {
            throw new IllegalStateException("cannot convert `" + className + "` to " + targetClass);
        }

        // 3. create instance
        return newInstance(aliasName, cls, propNames);
    }