Provide collection types for apache-commons

Currently it seems that the CommonsConfigPropertySource doesn't provide collections because it gets the property by getString(key) from commons configuration:

public PropertyValue get(String key) {
return PropertyValue.of(key, commonsConfig.getString(key), getName());
}

So for a list like [Value1,Value2,Value3] this will only return Value1.

Would be great if also collections (at least lists) would be supported.