This will require licensing from Oracle and formal confirmation of full Java SE compatibility test suite. Otherwise they will sue JetBrains to NPE. They skipped RoboVM and other minor implementations due to insignificance and short life time.
I'm not sure why this require licensing. Calling this implementation "Java SE" implementation will require passing JCK. Can Oracle sue product not tagged as "Java SE"? If can, is this so hard to pass JCK?
Tell this to guys from excelsior. With stable implementation for x86, x64 and arm took like 4 years.
I'm not sure how they actually implemented their AOT compiler. Did they write codegen themselves or they used LLVM? In the first case they had to create a good codegen, and creating a good efficient codegen is very complicated task. Also, they support class loading, therefore they have JIT as well. Creating subset of JDK (say, without ability to create new class loaders) won't require JIT, which reduces amout of work. Also, did they implement JDK classes themself? If they used forked OpenJDK and licensed their product under LGPL, they also could reduce amount of work. Also, they support threads and memory model, which is quite complicated, even with LLVM. I believe, it's possible to create something like green threads upon runtime coroutines.
This is directly forbidden by licensing. This kind of cuts are formal reason for Oracle - Google ongoing trial.
Can you provide a proof link? If this is the case, can they sue for automatic tool that takes only part of JDK and compiles it to native code? I guess it's all about distribution, I don't say about distributing cut version of JDK.