ASSERT.assertNotNull verhindert MayProduceNPE Warnung nicht

[tomg246]

Is your feature request related to a problem? Please describe.
After checkong an object via AssertProvider.ASSERT.assertNotNull(Obj o) intelliJ nethertheless shows the "Method invocation may produce NullPointerException" warning

Describe the solution you'd like
use @contract("null -> false") for assertNotNull

[martingrossmann]

The @Contract annotation belongs to the dependency org.jetbrains:annotations which is not part of Testerra. This could helpful if all Testerra users use IntelliJ. But Testerra is a common Java Framework. I'm not sure if we have to add special helpers for certain IDEs.
Of course we could provide some hints how to configure your IDE for best experience. Is there another solution for IntelliJ? Well, the IDE already knows the Assert methods of Junit and TestNG. Could we extend that rules?