@GetMapping("/multiValue")
public ResponseEntity<String> multiValue(
@RequestHeader MultiValueMap<String, String> headers) {
headers.forEach((key, value) -> {
LOG.info(String.format(
"Header '%s' = %s", key,
value.stream().collect(Collectors.joining("|"))));
});
return new ResponseEntity<String>(
String.format("Listed %d headers", headers.size()), HttpStatus.OK);
}