JBoss Messaging file authorship guidelines
If you make any significant~ change (addition or modification, not deletion) to a file add your name and email address to the bottom of the authors list in the file.
If you create a new class/interface and it is a completely new concept with nothing copied and pasted from anywhere else, then just add yourself as the sole author.
If the class/interface is a new class/interface but contains methods or declarations that come from other classes/interfaces please, then this is also considered a modification (refactoring), so please add all the authors from the other classes/interfaces to the new file and add yourself as an author too at the bottom of the list like in 1)
~ Significant is open to interpretation, and IANAL so please use your best judgement.
But in general, if the change can be seen as an original, creative work then it's significant. Correcting a typo, error in a SQL statement or reformatting of a file is unlikely to be a creative work.