HiddenField module can now accept setterCanReturnTItsClass attribute;
When set to true it means that setter methods can return either instance
of the class in which they are declared or void, which is different from
current behaviour where setters must return void.

Minor clean up to satify checkstyle rules.
Merge branch 'ExtendedSetter' of https://github.com/priimak/checkstyle into ExtendedSetter