Saving PropertiesConfiguration using UTF-8 encoding doesn't work

I created JUnit test http://goo.gl/GCwi2, that uses two methods to save PropertiesConfiguration (with property value containing utf-8 characters) into file:
1) propsConf.save(file); // propsConf.setEncoding("UTF-8") was called before
and
2) propsConf.save(fileOutputStream, "UTF-8");

Test shows that file doesn't contain UTF-8 characters. Instead saved file contains unicode escapes of non ISO-8859-1 characters.

This seems wrong, as documentation on setEncoding() method says:
"Set the encoding used to store the configuration file".
PropertiesConfiguration.setEncoding() method currently seems to affect only loading the configuration.

I added one test method that shows that even java.util.Properties class saves the same property value without any problems using utf-8 characters (not unicode escapes that it ) when using smth like that:
props.store(new OutputStreamWriter(fos, "UTF-8"));

It looks like a bug to me, or did i misunderstood smth?