1. Thing's most of those types provide no value in being spelled out like that. The ones on the methods have documentary advantages, but that's about it, the rest is magical invocations to make a stupid compiler happy.
2. There's also a gain from the framework being able to map things to each other without being told explicitly. `@PathParam("uid")` for instance, it's only there because the framework has no way to match the parameter name `uid` to the URL-extracted parameter `uid`. Likewise with HTTP methods being part of the routing instead of a separate annotation, in part.
3. Java's APIs and type system, such as implicit nulls and not being able to use arbitrary types in boolean contexts
2. There's also a gain from the framework being able to map things to each other without being told explicitly. `@PathParam("uid")` for instance, it's only there because the framework has no way to match the parameter name `uid` to the URL-extracted parameter `uid`. Likewise with HTTP methods being part of the routing instead of a separate annotation, in part.
3. Java's APIs and type system, such as implicit nulls and not being able to use arbitrary types in boolean contexts