RequestTracingFilter implements Filter { protected List<String> getUserIdHeaderKeys() { return userIdHeaderKeysFromInitParam; }  @Override @SuppressWarnings("RedundantThrows") void init(FilterConfig filterConfig); @Override void destroy(); @Override void doFilter(ServletRequest request,
                         ServletResponse response,
                         FilterChain filterChain); static final String FILTER_HAS_ALREADY_EXECUTED_ATTRIBUTE; @Deprecated
    static final String ERROR_REQUEST_URI_ATTRIBUTE; static final String USER_ID_HEADER_KEYS_LIST_INIT_PARAM_NAME; static final String TAG_AND_SPAN_NAMING_STRATEGY_INIT_PARAM_NAME; static final String TAG_AND_SPAN_NAMING_ADAPTER_INIT_PARAM_NAME; }
@Test public void getUserIdHeaderKeys_returns_userIdHeaderKeysFromInitParam_field() { RequestTracingFilter filter = new RequestTracingFilter(); List<String> expectedUserIdHeaderKeys = Arrays.asList(UUID.randomUUID().toString(), UUID.randomUUID().toString()); filter.userIdHeaderKeysFromInitParam = expectedUserIdHeaderKeys; List<String> result = filter.getUserIdHeaderKeys(); assertThat(result).isSameAs(expectedUserIdHeaderKeys); }