xgboost-predictor/src/main/java/biz/k11i/xgboost/tree/RegTreeImpl.java
@Override
    public float getLeafValue(FVec feat, int root_id) {
        Node n = nodes[root_id];
        while (!n._isLeaf) {
            n = nodes[n.next(feat)];
        }

        return n.leaf_value;
    }
@Override
    public float getLeafValue(FVec feat, int root_id) {
        Node n = nodes[root_id];
        while (!n._isLeaf) {
            n = nodes[n.next(feat)];
        }

        return n.leaf_value;
    }
Retrieves nodes from root to leaf and returns leaf value.

@param feat    feature vector
@param root_id starting root index
@return leaf value