changing a method interface

[Brad Walker]

I believe there is a process for changing the interface of a particular
method..

Say for example, I wanted to change the following
    public void setWebServiceIds(Set ids)
to
    public void setWebServiceIds(Set<String> ids)

Besides the obvious code change, what else would I need to do? I think
there is some versioning "stuff" but I know nothing about it..

Thanks.

-brad w.