An instantiation of the jcore-db-reader that uses the jcore-xml-mapper to retrieve and parse PubMed XML
from a PostgreSQL database. The XML format of retrieved documents is expected to follow the PubMed/MEDLINE XML
schema
that was used beginning from 2017. I.e. the root document of a document must be PubmedArticle and not,
as it was for MEDLINE until 2017, MedlineCitation.