The return type for `tag` in PoolEntry and AnnotationValue are `byte` and `char` respectively, which does not match the constant types. And the `byte` for PoolEntry will be erroneously negative if the tag value goes beyond 127 (it is allowed to be an unsigned int).
This also brings consistency with other discriminator values, such as `StackMapFrameInfo::frameType`, `TypeAnnotation.TargetType::targetTypeValue`.