Consider inheritance when checking models

[msridhar]

We should be able to leverage inheritance when writing models for librarys. E.g., Collections.toArray(T[]) is specified to throw an NPE whenever the parameter is null. Right now, we need to add a model for Collections.toArray, ArrayDeque.toArray, LinkedList.toArray, etc. to get full safety. It'd be nice to just add a model for Collections.toArray and then catch this for any overriding method. Would need to be careful about performance when implementing this.

[kageiit]

@msridhar we are seeing the word performance thrown around a lot during many tickets failed against nullaway, but we dont seem to have a concrete way to measure this. Can we setup a profiling sample using jmh in this repo that can we run as part of travis and give us numbers on what the performance change looks like on PRs? or atleast a way for us to run manually?

[msridhar]

@kageiit opened #87 on benchmarking / profiling. Not sure we can trust numbers from Travis, but at least for running locally it should be useful.