StaticHandler setAlwaysAsyncFS(true),if it can't find a file,it throw a exception rather than 404 error

[gaoweiqiao]

When router.get(STATIC_URL).handler(StaticHandler.create().setAlwaysAsyncFS(true));
If it can't find a file, it throws a java.nio.file.NoSuchFileException rather than 404 error.
The exception may be thrown in if (alwaysAsyncFS || useAsyncFS) {
fs.props(file, resultHandler);
} in getFileProps method in StaticHandlerImpl class.

When I setAlwaysAsyncFS(false) or I don't call setAlwaysAsyncFS(), if it can't find a file ,it return 404 error.That's fine.