Summary:
The bridge implementation on React Android does not currently support boxed numeric/boolean types (the equivalent of NSNumber arguments on iOS), nor does Java support Objective-C's nil messaging system that transparently casts nil to zero, false, etc for primitive types.
To avoid platform incompatibilities, we now treat all primitive arguments as non-nullable rather than silently converting NSNull -> nil -> 0/false.
We also now enforce that NSNumber * objects must be explicitly marked as `nonnull` (this restriction may be lifted in future if/when Android supports boxed numbers).
Other object types are still assumed to be nullable unless specifically annotated with `nonnull`.
Summary:
This diff adds support for enforcing nullability in the arguments for exported methods.
We previously supported use of the nullable/nonnull attributes on method arguments, but didn't do anything to ensure that they were respected.
Now, if an argument is marked as nonnull, and a null value is sent for that argument, it will display a redbox.
In future, nonnull will be assumed by default, but for now we assume that un-annotated arguments can be null (to avoid breaking existing code).
Nick Lockwood