Overriding hashCode with a class with two generics fields

You are already relying on the left and right equals methods so why not also rely on their hashcodes?

@Override
public int hashCode()
{
    final int prime = 31;
    int result = 1;
    result = prime * result + (left ==null? 0 : left.hashCode());
    result = prime * result + (right ==null? 0 : right.hashCode());
    return result;
}

Don’t reinvent the wheel.

Just use return Objects.hash(left, right);