@Override
            public CompletableFuture<Void> shutdown() {
                final CompletableFuture<Void> f1;
                final CompletableFuture<Void> f2;
                try {
                    f1 = AccessLogWriter.this.shutdown();
                } finally {
                    f2 = after.shutdown();
                }
                return CompletableFuture.allOf(f1, f2);
            }
Returns a new {@link AccessLogWriter} which combines two {@link AccessLogWriter}s.
core/src/main/java/com/linecorp/armeria/server/logging/AccessLogWriter.java