Today I discovered the fault in my code and assumption. To make sure it filters on type, avoiding the field name conflict, the following code has to change from

FullTextQuery fullTextQuery = fullTextSession.createFullTextQuery(luceneQuery);

to

FullTextQuery fullTextQuery = fullTextSession.createFullTextQuery(luceneQuery, ReportAccessArea.class);

Without specifying the class for type filtering, results may come from other indexes as well. Specifying the class when creating the query builder does not enable type filtering, which I wrongly thought.

I hope this clarifies things and I am sorry for creating a bug for a user mistake.