public boolean isNegative() {
        return negative;
    }
Use {@link Joystick#assignAxis(java.lang.String, java.lang.String, int) }
instead.

@param joyId which joystick
@param axisId which joystick axis
@param negative true to negate input values, false to leave unchanged
jme3-core/src/main/java/com/jme3/input/controls/JoyAxisTrigger.java