@Article{demo,
  author = {First1 Last1
  First2 Last2
  First3 Last3},
}

renders in JabRef as follows:

But is should check: Hey, there are strings separated by one space - and blocks separated by multple spaces. One space: one author block - multiple spaces: sepearates author block

Task

• Add test to org.jabref.model.entry.AuthorListTest
• Modify org.jabref.logic.importer.AuthorListParser#parse - add heuristics at the beginning of the method