in src/main/java/org/apache/sling/testing/mock/jcr/MockNode.java [388:396]
private void addItemOrRemoveIfValueNull(ItemData itemData, Object value) throws RepositoryException {
if (value == null) {
getMockedSession().removeItem(itemData.getPath());
}
else {
getMockedSession().addItem(itemData);
}
this.itemData.setIsChanged(true);
}