  @Test
  public void testInject() {

    Map<String, String> carrier = new HashMap<>();
    TextMapAdapter textMap = new TextMapAdapter(carrier);
    long traceIdLow = 1;
    long spanId = 2;
    long parentId = 3;
    long traceIdHigh = HexCodec.hexToUnsignedLong("c281c27976c85681", 0, 16);
    JaegerSpanContext spanContext = new JaegerSpanContext(traceIdHigh, traceIdLow, spanId, parentId, (byte) 0);

    traceContextCodec.inject(spanContext, textMap);

    String expectedTraceContextHeader = "00-c281c27976c856810000000000000001-0000000000000002-00";
    assertEquals(1, carrier.size());
    assertNotNull(carrier.get(TRACE_PARENT));
    assertEquals(expectedTraceContextHeader, carrier.get(TRACE_PARENT));
  }