IDEA inspection is not correct

Tree.java

import java.util.Iterator;
import java.util.NoSuchElementException;

final class Tree<T> {

    private final T elem;
    private final Tree<T> parent;

    private Tree(T elem, Tree<T> parent) {
        this.elem = elem;
        this.parent = parent;
    }

    /** Iterator from current tree element to it's root. */
    public Iterator<T> toRoot() {
        return new Iterator<T>() {
            Tree<T> curr = Tree.this;

            @Override
            public boolean hasNext() {
                return curr.parent != null;
            }

            @Override
            public T next() {
                if (!hasNext()) {
                    throw new NoSuchElementException();
                }

                final T res = curr.elem; // IDEA inspection: Local variable 'res' is redundant
                curr = curr.parent;
                return res;
            }
        };
    }
}

IDEA version information:

IntelliJ IDEA 2016.2.2
Build #IC-162.1628.40, built on August 16, 2016
JRE: 1.8.0_40-b25 amd64
JVM: Java HotSpot(TM) 64-Bit Server VM by Oracle Corporation