HeaderFilter implements Filter { public List<String> getFilteredHeaderNames() { return filteredHeaderNames; } HeaderFilter(List<String> filteredHeaderNames); List<String> getFilteredHeaderNames(); @Override void init(FilterConfig filterConfig); @Override void doFilter(ServletRequest request, ServletResponse response, FilterChain chain); @Override void destroy();  }
@Test public void allows_null_argument() { HeaderFilter filter = new HeaderFilter(null); assertNotNull(filter.getFilteredHeaderNames()); }