Leetcode 116, Populating Next Right Pointers in Each Node

public void connect(TreeLinkNode root) {
if(root == null){
return;
}
if(root.left != null){
root.left.next = root.right;
}
if(root.right != null){
if(root.next != null){
root.right.next = root.next.left;
}
}
connect(root.left);
connect(root.right);
}