presto-main/src/main/java/io/prestosql/metadata/InternalNode.java/InternalNode/equals
class InternalNode:    @Override
    public boolean equals(Object obj)
    {
        if (this == obj) {
            return true;
        }
        if ((obj == null) || (getClass() != obj.getClass())) {
            return false;
        }
        InternalNode o = (InternalNode) obj;
        return nodeIdentifier.equals(o.nodeIdentifier);
    }