public boolean hasChild(Spatial spat) {
        if (children.contains(spat)) {
            return true;
        }

        for (Spatial child : children.getArray()) {
            if (child instanceof Node && ((Node) child).hasChild(spat)) {
                return true;
            }
        }

        return false;
    }
determines if the provided Spatial is contained in the children list of
this node.

@param spat
           the child object to look for.
@return true if the object is contained, false otherwise.
jme3-core/src/main/java/com/jme3/scene/Node.java