presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/metadata/RaptorNode.java/RaptorNode/RaptorNode
class RaptorNode:    public RaptorNode(int nodeId, String nodeIdentifier)
    {
        this.nodeId = nodeId;
        this.nodeIdentifier = requireNonNull(nodeIdentifier, "nodeIdentifier is null");
    }