Custom type qualifiers via annotations on Java types

by its author, who also creates plug-ins to check and enforce those semantics. Those plug-ins can operate at compile time and load time | making guarantees about run-time behavior requires load-time checking, but compile-time checking is useful as an early check and is more convenient for programmers. This document explores implementation strategies for plug-ins that check annotations. These strategies are equally valid for Java's original annotations and for the new extended annotations. Both compile-time and load-time processing are outside the scope of the annotations proposal, but are presented here as an example of how annotations on types might be used. The processors described here do not require any further changes to Java beyond those described in the \Type annotations" document.