Converter, getErrorMessage and variants

Hi Jetbrainers,

I'm writing because I need some clarification with regards to my usage
of the com.intellij.util.xml.Converter. I would like to provide some
values for the user to choose from based on some content from the
current file but also some content located in another file. The content
form the current file I do get by calling
convertContext.getInvocationElement().getParentOfType(MyClass.class,
true)  and then call the respective method on that object. But is it
also the right place to get the content of the other file within this
method or should I create a CompletionContributor which addeds to the
current variants?

Best regards,

Jens