Method breaks a rule: only one type of response. It returns two different values. Depends on some condition.

@GetMapping("get/

{templateName}

")
public ResponseEntity<?> get(@PathVariable String templateName) {
Optional<Template> template = service.get(templateName);
if (!template.isPresent())

{ HttpHeaders headers = new HttpHeaders(); headers.setContentType(MediaType.TEXT_PLAIN); return new ResponseEntity<>(TEMPLATE_NOT_FOUND_MSG, headers, HttpStatus.NOT_FOUND); }

return new ResponseEntity<>(template, HttpStatus.OK);
}