@Override
    public void initialize() {
        if (inited)
            throw new IllegalStateException("Input already initialized.");

        inited = true;
    }
DummyInput as an implementation of <code>Input</code> that raises no
input events.

@author Kirill Vainer.
jme3-core/src/main/java/com/jme3/input/dummy/DummyInput.java