public boolean isRoot() {
        return parent == null;
    }
<p>Returns whether or not this <code>TraceNode</code> is a root node (i.e. it has no parent).</p>

@return <code>true</code> if {@link #parent()} returns <code>null</code>
vespajlib/src/main/java/com/yahoo/yolean/trace/TraceNode.java