Agreed. <code>@Nullable</code> is just an additional notification for users without side affects in the static analysis, hence it's safe to use it here.

* I'll replace return annotations in <code>replaceMacro</code>, <code>ensureEndsWith</code> and <code>intern</code>. 
* <code>nullify</code>, <code>fixEmpty</code>, <code>fixEmptyAndTrim</code> methods are debatable due to their common usage in <code>DataBoundConstructor</code> , but seems the <code>@Nullable</code> is preferable as well
* Other methods like <code>getWin32ErrorMessage</code> and <code>resolveSymlink</code> should use <code>@CheckForNull</code>, because Javadoc defines the platform-dependent behavior, which should be handled by users