http://hibernate.org/~emmanuel/validation mentions @Length in example 2.2.

However, in "Chapter 6. Built-in Constraint definitions" @Length is not mentioned. Also the Hibernate Validator 4.0.0.alpha2 release doesn't contain @Length.

I tried @Size instead of @Length and this works fine.

@Size and @Length overlap.
@Length is a "custom" constraint. I need to get over the spec examples to clarify that.