@Test
public void testExtract_mixedCaseIsLowered() {

    Map<String, String> mixedCaseHeaders = new HashMap<>();
    mixedCaseHeaders.put("Ot-tracer-spanid", Long.toHexString(1));
    mixedCaseHeaders.put("Ot-tracer-traceId", Long.toHexString(2));
    mixedCaseHeaders.put("ot-Tracer-sampled", "true");
    TextMapPropagator subject = new TextMapPropagator();
    SpanContext span = subject.extract(new TextMapExtractAdapter(mixedCaseHeaders));
    assertNotNull(span);
    assertEquals(span.getSpanId(), 1);
    assertEquals(span.getTraceId(), 2);
}