translate kotlin to java

I'm using a screenshot library (in Github) and it is has been written in Kotlin(I don't know Kotlin very well).

<https://github.com/bolteu/screenshotty>

I don't know how to translate to Java a part of code. in the read me file :

val screenshotResult = screenshotManager.makeScreenshot()
val subscription = screenshotResult.observe(
   onSuccess = { processScreenshot(it) },
   onError = { onMakeScreenshotFailed(it) }
)

It says that you can get a screenshot object from "it"? how can I do that? please help me...

and how can I translate this code to Java :

fun show(screenshot: Screenshot) {
   val bitmap = when (screenshot) {
      is ScreenshotBitmap -> screenshot.bitmap
   }
   screenshotPreview.setImageBitmap(bitmap)
}