The defaultcheck plugin is used to check whether nullable is not used incorrectly.
For instance:
An error is caused if a nullable field:
- has a default value,
- is an enum which does not start at zero,
- is used for an extension,
- is used for a native proto3 type,
- is used for a repeated native type.
An error is also caused if a field with a default value is used in a message:
- which is a face.
- without getters.
It is enabled by the following extensions:
For incorrect usage of nullable with tests see:
github.com/gogo/protobuf/test/nullableconflict