Why the heck did someone came up with an annotation named Foo that can be applied to a class only if it implements another interface, also named Foo?!

That leaves no choice, but to use an ugly, fully qualified name for one of it.

A case in point is that the example in the seam reference will not compile (section 29.2. Annotations):

@Converter
public class ItemConverter implements Converter {

How about deprecating those names and introducing something like @ConverterComponent