The HelloRadioButton Sample used for Accessibility/FX testing has one active control, a pair of associated RadioButtons.

At least three controls are needed to exercise and test focus tabbing (TAB and SHIFT-TAB) and other keystroke commands.

For example, a larger set of RadioButtons could be added, and one other control, possibly a simple Button to clear the radio buttons.
 
When the focus is on an unset RadioButton, pressing the SPACEBAR will set that RadioButton. The current sample will not accomodate this test or the focus tabbing tests.
 
See

https://wiki.openjdk.java.net/display/OpenJFX/Keyboard+Navigation

 under "RadioButton" (SPACEBAR, TAB & SHIFT-TAB).

The HelloRadioButton Sample is run from Hello.jar as follows:

java -cp Hello.jar hello.HelloRadioButton

RULE tests/jaws/RadioButton any any
RULE tests/narrator/RadioButton any any
RULE tests/voiceover/RadioButton any any