A reply on my gist nicely solved that problem - thank you very much!!!, which unmasked a new one.
The revised INSERT now reads
INSERT INTO public.paragraph (doc_id, data) VALUES($1, $2) RETURNING id
but RETURNING is yielding null from row.getlong("id")
This page in the vert.x documentation
suggests
INSERT INTO public.paragraph (doc_id, data) VALUES($1), ($2) RETURNING id
why the difference in VALUES remains a mystery, but, still, RETURNING is failing,even though the database clearly has the object and its "id"
This one's a puzzle!
Thanks in advance for ideas.
Jack