How can I use Redisson Write-through caching strategy with an auto-generated PK

I am planning to use Redis with Redisson as a caching layer between my Java app and a PostgreSQL DB. I have a table called Nodes looking like this:

CREATE TABLE nodes(node_id bigint GENERATED BY DEFAULT AS IDENTITY(START WITH 1 INCREMENT BY 1),node_name varchar(100) NOT NULL,PRIMARY KEY (node_id))

I want to use Redisson RMap persistence to cache this structure. My goal is to have an rmap looking like this:

Rmap<Integer, Node> 

where the key is the PK, and the value is the node itself.

I want to use read-through and write-trhough strategies for caching this Rmap, by using the MapLoader and the MapWriter.

Then, I want to have a Java method which should create and persist a node.

public void createNode(String nodeName) {  Node node = new Node();  node.setName(nodeName);  // how can I put elements in the rmap since,   // the PK will be available after the INSERT statement will run?  rmap.put(?, node);}

And here comes the problem. Since the PK is auto-generated from Postgres, how can I use the RMapWriter to insert a node, since, for putting elements in the RMap I need the key, which I don't have until the insert statement will run?