Hi. Anyone could tell me what this type means?

val results: (MutableList<(MutableMap<String!, Any!>..Map<String!, Any!>?)>..List<(MutableMap<String!, Any!>..Map<String!, Any!>?)>?)

especially the double dots. The function that returns that type was actually returning this java type,

List<Map<String, Object>>

@blindbox it's a bad case of a platform type http://kotlinlang.org/docs/reference/java-interop.html#null-safety-and-platform-types

Interesting. Is this type specifically due to java interop, or does it also mean that we can define a type that is as such?

It's just for Java interop, you can't declare it.

@blindbox Nope, there's no special syntax for them, they're just a notation for tools and error messages. They're called Platform Types, see https://kotlinlang.org/docs/reference/java-interop.html#null-safety-and-platform-types