Add filter for Kotlin not-null assertion operator

[Godin]

https://groups.google.com/d/msg/jacoco/V4z41kgUnK8/JbqDkAZ5FgAJ

[Godin]

BTW IMO there is no need to generate explicit null-check in cases such as

fun example(x: String?) {
  val y:Int  = x!!.length
  // ...
}

because invokevirtual anyway will throw NPE

         0: aload_1
         1: dup
         2: ifnonnull     8
         5: invokestatic  #12                 // Method kotlin/jvm/internal/Intrinsics.throwNpe:()V
         8: invokevirtual #18                 // Method java/lang/String.length:()I
        11: istore_2

while definitely useful in cases such as

fun example(x: String?) {
  val y: String = x!!
  // ...
}

@goodwinnk maybe this is something what can be improved in Kotlin compiler?

[goodwinnk]

@Godin There's a plan to unify different null checks in Kotlin in favor to simply throwing Java NPE: https://youtrack.jetbrains.com/issue/KT-22275

[Godin]

@goodwinnk good to know, thanks!