What is the difference between `Type!` and `Type?`...

# announcements

[segfalt]

What is the difference between Type! and Type? -- I seem to see a lot of the former when interoping with Java code.

[diesieben07]

String! is a platform type: https://kotlinlang.org/docs/reference/java-interop.html#null-safety-and-platform-types

[Dalinar]

I'm still confused as to when you have to explicitly declare the platform type returned by your fun and when it is optional, seems to me it is not every time?

[edwardwongtl]

This type exist because in Java everything can be null, it is always save to make them as Type? if you are not sure.