It's true (so I hear) that C# has been ahead of Java on this for a while, but I think the JVM is ahead of the CLR in terms of ecosystem. If you like F#, maybe try Scala on the JVM.
Did you use Java 8 last time you worked with Java? And ideally, maybe something like lombok or scala case classes or protobufs to make value object classes easy to declare?
Also, don't use Java2D then. There's better libraries for that. Maybe it's technically considered a core library, but I wouldn't consider it important