[XWayland] crash when an AWT ScreenCast session overlaps with an FX ScreenCast session

Internally the ScreenCast session keeps open for 2s.

This is to reduce overhead in case of frequent consecutive screen captures.

There is a crash when an AWT ScreenCast session overlaps with an FX ScreenCast session.
E.g. java.awt.Robot#getPixelColor() and javafx.scene.robot.Robot#getPixelColor() are called within 1 second.

This may require a fix on the JFX or OpenJDK side, or both.