Kotlin vs. Java
Why don't the nullability examples use Java's Optional?This code:  if (nullableVariable != null) {
      boolean success = nullableVariable.someMethodCall()
      if (success) {
          return success
      } else {
          return fallbackIfNullMethodCall()
      }
  } else {
      return fallbackIfNullMethodCall()
  }


Could also be written something like this:  result = Optional.ofNullable(nullableVariable)
                   .map(NullableType::someMethodCall)
                   .orElse(fallbackIfNullMethodCall());

Sure, it's no Elvis operator, but it's a lot more readable than the "standard" if/else structure of traditional Java. If we're comparing Java and Kotlin, we should at least give Java a fair chance. I dislike the verbosity of the Optional wrapper, but it's a lot better than if/else checking.