I will create a Java agent which does bytecode manipulation to check that non-thread-safe classes (i.e. classes annotated with JSR-305's @NotThreadSafe) are used only from one thread. Unit tests for bytecode manipulation can be written using a custom class loader, which transforms only the bytecode of a selected class, and a bunch of "guinea pig" classes [1] to be used as test data.
[1] See GOOS page 284.
