This fixes some issues I found while updating this code base, e.g.
this removes types a method really does not return.
Change-Id: I19457e7bf88945eec958bf53e0b76a7585715a45
Most modern IDEs as well as documentation generators understand the
keywords "false" and "true", when a bool can only be one of the two.
Change-Id: I83dd1f0cc0802fa74ee35e7ca7425615230a767f
Formatters based on presentation models for
individual event emails and digest (daily, weekly)
plain text emails.
Bug: T121067
Change-Id: I4eceaf521315adab7429a8a73ffca70ebcddab86