Is getQueryStatistics() reliable

Hi all, I am working on a unit test for an extension to apoc I started long ago.
So long, I am using a branch based upon neo 3.3

My test fails because t.getQueryStatistics().getNodesDeleted() is always zero.

So I was wondering if getQueryStatistics was reliable at this time.
I presume I am using it wrong.

Here is my call and assert
Result t = db.execute("CALL apoc.nodes.removebylabels", params) ;
assertEquals( baseNbr , t.getQueryStatistics().getNodesDeleted() );

Thank you