Migration to the Type Checking Verifier
Wei Tao wrote a nice introduction to the Type Checking Verifier enabled since Mustang build 45. https://jdk.dev.java.net/verifier.html
I believe that there is lot of "legacy" libraries that unlikely will be recompiled and as a result woun't be able to benefit from this feature. So, it would be a good idea to have some kind of utility that will add StackMapTable attribute to the old bytecode. That will be similar to the preverifier tool used for CLDC 1.1 where this idea had been introduced in the first place.
Perhaps this utility could part of JSR 199, so other tools, such as profilers, aop and orm engines could use this API.