Better Java properties handling

Luigi R. Viggiano provides OWNER API, a clever, better way to handle Java properties.

Essentially he maps properties in a general sense onto Java interfaces, using annotations to guide sourcing and processing. This is going directly into my projects.

I wrote a similar library based on interfaces to access properties, but using inheritance, implementation and generics with a set of helper base classes. His approach is superior.

@Sources({ "file:~/.myapp.config", 
           "file:/etc/myapp.config", 
           "classpath:foo/bar/baz.properties" })
public interface ServerConfig extends Config {
    @Key("server.http.port")
    int port();

    @Key("server.host.name")
    String hostname();

    @Key("server.max.threads");
    @DefaultValue("42")
    int maxThreads();
}

Interfaces to access properties is right. Among benefits you get strong typing of configuration and your IDE provides code completion.