docs: public void removeChild(AttributeId attribute) {
        if (children == null) {
           throw new IllegalArgumentException("No child found : " + attribute);
        }
        AttributeNode<AttributeMetadata, AttributeId> child = children.get(attribute);
        if (child == null) {
           throw new IllegalArgumentException("No child found : " + attribute);
        }
        children.remove(attribute);
        rebuildChildrenArray();
     }