@Test
public void testExtractEmptyHeaders() {

    Map<String, String> headers = new HashMap<>();
    headers.put("X-B3-SpanId", "");
    headers.put("X-B3-TraceId", "");
    B3Propagator subject = new B3Propagator();
    SpanContext span = subject.extract(new TextMapExtractAdapter(headers));
    assertNull(span);
}