### Question:
RequestProviderService { @NotNull public String getAcceptHeader() { String acceptHeader = getHeader(ACCEPT_HEADER); if (acceptHeader == null) { return MediaType.ALL_VALUE; } return acceptHeader; }  Optional<Boolean> resolveTppRedirectPreferred(); RequestData getRequestData(); PsuIdData getPsuIdData(); @NotNull UUID getInternalRequestId(); @Nullable String getInstanceId(); String getInternalRequestIdString(); UUID getRequestId(); String getRequestIdString(); boolean isRequestFromPsu(); boolean isRequestFromTPP(); String getPsuIpAddress(); String getTppRedirectURI(); String getTppNokRedirectURI(); String getOAuth2Token(); String getTppRolesAllowedHeader(); @NotNull String getAcceptHeader(); String getContentTypeHeader(); String getEncodedTppQwacCert(); String getTppBrandLoggingInformationHeader(); Boolean getTppRejectionNoFundsPreferred();  }### Answer:
@Test void getAcceptHeader() { when(httpServletRequest.getHeader(ACCEPT_HEADER)).thenReturn(ACCEPT_HEADER_JSON); String actual = requestProviderService.getAcceptHeader(); assertEquals(ACCEPT_HEADER_JSON, actual); }
@Test void getAcceptHeader_withNullValue_shouldReturnAny() { String actual = requestProviderService.getAcceptHeader(); assertEquals(ACCEPT_HEADER_ANY, actual); }