Generally, that was the idea yes.

I think "public" is the implicit default, so really we are talking about identifying classes, methods, etc that fall outside the scope of access defined by their java modifiers. So specifically SPI and internal from that list. Essentially denoting the danger in relying on these signatures in terms of compatibility.

A tangential annotation I personally would like to see added is @Incubating to denote new APIs that are under development. Its an idea I picked up from the Gradle team. It has the same intent of warning about compatibility.