How to read span attributes/tag data(url.path) in the opentelemetry java agent extension

Question

public void onStart(Context parentContext, ReadWriteSpan span) {
    span.setAttribute("custom", "demo");
    System.out.println("TEST21 -> " + span.getInstrumentationScopeInfo().getAttributes().asMap());
    System.out.println("Test22-> " + span.getName());
    System.out.println("MAP VALUES ARE-> " + span.getParentSpanContext().getTraceState().asMap());
    System.out.println("MAP2 Values are -> " + span.getSpanContext().getTraceState().asMap());
    System.out.println("ANAJSC " + span.getSpanContext().getTraceState().get("url.path"));
    System.out.println("parent " + span.getParentSpanContext().getTraceState().get("url.path"));
    System.out.println("child " + span.getSpanContext().getTraceState().get("url.path"));
    System.out.println("ch " + Span.fromContext(parentContext).getSpanContext().getTraceState().get("url.path"));
    System.out.println("MIGHT " + Java8BytecodeBridge.currentSpan().getSpanContext().getTraceState().asMap());
    System.out.println(
            "MIGHT2 " + Java8BytecodeBridge.currentSpan().getSpanContext().getTraceState().get("url.path"));

}

Expecting the tag data like url.path in string format.. All the println statements are giving null or empty values