@Nullable @NotEmpty and Identifiers (and the like)

[Rod Widdowson]

So here's a question, mostly for Chad.

As I've been working through the IdP unit tests I've been adding the obvious Annotations to code which predates the conventions in
https://wiki.shibboleth.net/confluence/display/DEV/Java+Coding+Conventions being solidified.

A pretty common paradigm is:

class Foo extends AbstractInitializableComponent {

  private String thing;
 
  public String getThing() {...}

  public void setThing(String newThing) {...}

  public void doInitialize() { 
    ...
    if (null == thing) {
	throw("thing cannot be null of empty");
    }

}

'thing' is often the identifier, but not always.

My question is, with what annotation should getThing() be garnished? Strictly speaking it should be @Nullable, but we do add the
test to make sure that after initialization it will never be null or empty.  There is obvious code and/or annotations which can be
added to make sure that getThing() will never return null with that in place stage we could make getThing @NonNull @NotEmpty.

But should we or do we just live with getThing() being @Nullable.

Note that I am *NOT* proposing that we add a new annotation.