public interface Get
When stapler is querying a Java object to see which properties it has
it normally uses reflection to see if there is a field or getter with the
corresponding name which it can use.
You obviously can't do this on a JRuby object, so instead Stapler and Jenkins
will look and see if it has a get(String) method and if so, use that for
property lookup.
JRuby proxies include this interface to support this.