    @Test
    public void givenCustomTag_whenOnRequest_thenItShouldNotAddTag() {

        decorator = new ServletFilterHeaderSpanDecorator(headerEntries, "HEADER.");
        Mockito.when(httpServletRequest.getHeader("If-Match")).thenReturn("10");

        decorator.onRequest(httpServletRequest, span);
        Mockito.verify(span).setTag("HEADER.if-match", "10");
    }