Author or editor shouldn't be mandatory

[Alberto Gallardo]

Not relevant for our use cases, but a reference list could contain references to entries with no identified author or editor. See e.g. APA Publication Manual 6th, Ch. 7.02, example 30.

Marked as trivial because it doesn’t impact our system yet.

[Daniel Zoller]

a publication should always have an author/editor in my point of view

nevertheless, changing the author and editor field to be optional is not so easy, because the interhash and intrahash calculations depend on this value.

see #2885

[Mario Holtmüller]

More information about the mentioned hashes can be found here: https://www.bibsonomy.org/help_en/InterIntraHash

[Alberto Gallardo]

Same as with #2885. I don’t need this (yet).