Bug 331649 - [compiler][null] consider null annotations for fields
Bug 382789 - [compiler][null] warn when syntactically-nonnull
  expression is compared against null
Bug 380896 - [compiler][null] Enum constants not recognised as being
  NonNull.
Bug 383368 - [compiler][null] syntactic null analysis for field
  references
Bug 388630 - @NonNull diagnostics at line 0