### Question:
DelegateCommand extends Service<Void> implements Command { @SuppressWarnings("unchecked") protected static Property<Throwable> checkExceptionProperty(ReadOnlyObjectProperty<Throwable> exceptionProperty) { if (exceptionProperty instanceof Property) { return (Property<Throwable>) exceptionProperty; } else { throw new RuntimeException( "Cannot use DelegateCommand in asynchronous mode because of an incompatible JDK version. Please report this to the mvvmFX developers at https: } } DelegateCommand(final Supplier<Action> actionSupplier);  DelegateCommand(final Supplier<Action> actionSupplier, boolean inBackground);  DelegateCommand(final Supplier<Action> actionSupplier, ObservableValue<Boolean> executableObservable);  DelegateCommand(final Supplier<Action> actionSupplier, ObservableValue<Boolean> executableObservable,
			boolean inBackground); @Override void execute(); @Override ReadOnlyBooleanProperty executableProperty(); @Override boolean isExecutable(); @Override final ReadOnlyBooleanProperty notExecutableProperty(); @Override final boolean isNotExecutable(); @Override final ReadOnlyBooleanProperty notRunningProperty(); @Override final boolean isNotRunning(); Supplier<Action> getActionSupplier();  }### Answer:
@Test public void testCheckExceptionProperty() { DelegateCommand delegateCommand = new DelegateCommand(() -> { return null; }); DelegateCommand.checkExceptionProperty(delegateCommand.exceptionProperty()); }