Extensions for java.util.Optional (KT-50484)

Co-authored-by: Ilya Gorbunov <ilya.gorbunov@jetbrains.com>

libraries/stdlib/jdk8/java9/module-info.java

@@ -3,6 +3,7 @@ module kotlin.stdlib.jdk8 {
     requires transitive kotlin.stdlib;
     requires kotlin.stdlib.jdk7;
 
+    exports kotlin.jvm.optionals;
     exports kotlin.jvm.jdk8;
     exports kotlin.collections.jdk8;
     exports kotlin.streams.jdk8;