Fix false positive "Null can not be a value of a non-null type"

Inferred type of receiver of orElse  is Optional<T & Any>
Generic descriptor is orElse(E!): E!
Substituted descriptor is orElse(T): T , and that is the problem.

Seems that E!  => (T & Any)!  gets expanded to just T  or T & Any , however it should be expanded to
(T & Any) .. (T & Any)?  => T & Any .. T & Any

T & Any is NotNullTypeParameter(T)

The problem is that (T & Any)?  is expanded to T & Any,
that is seems to be wrong.

 #KT-15236 Fixed

core/descriptor.loader.java/src/org/jetbrains/kotlin/load/java/typeEnhancement/typeEnhancement.kt

@@ -243,7 +243,8 @@ internal class NotNullTypeParameter(override val delegate: SimpleType) : CustomT
     }
 
     override fun replaceAnnotations(newAnnotations: Annotations) = NotNullTypeParameter(delegate.replaceAnnotations(newAnnotations))
-    override fun makeNullableAsSpecified(newNullability: Boolean) = this
+    override fun makeNullableAsSpecified(newNullability: Boolean) =
+        if (newNullability) delegate.makeNullableAsSpecified(true) else this
 
     override val isError: Boolean
         get() = false