SpringBoot GET endpoint handles spanish characters in headers by default, but POST endpoint doesn't recognize them

Current Behavior

POST and GET endpoint work with different encoding characters for HTTP headers.

While sending a header with Spanish word "muñoz" to a GET controller, it works as expected. But when sending the same header to a POST controller, the character encoding fails binding the String as "muÃ±oz".

Expected Behavior

For me both cases (GET and POST) should use the same character encoding

Minimal yet complete reproducer code(or URL to code)

https://github.com/egosumcarlos/demo-spring-headers-specials-chars-in-post/blob/master/src/main/java/com/example/demo/DemoController.java

Hit the controllers with:

curl --location --request GET 'http://localhost:8080/dummy' --header 'cust-full-name: muñoz'

curl --location --request POST 'http://localhost:8080/dummy' \
--header 'cust-full-name: muñoz' \
--header 'Content-Type: application/json' \
--data-raw '{
  "dni":"321"
}'

Comment From: wilkinsona

Thanks for the sample. Unfortunately, it doesn't appear to reproduce the behavior that you have described with both GET and POST receiving the header as muÃ±oz:

2022-07-20 11:16:03.021  INFO 27131 --- [ctor-http-nio-2] com.example.demo.DemoController          : header from GET muÃ±oz
2022-07-20 11:16:30.507  INFO 27131 --- [ctor-http-nio-3] com.example.demo.DemoController          : dto 321
2022-07-20 11:16:30.507  INFO 27131 --- [ctor-http-nio-3] com.example.demo.DemoController          : header from POST muÃ±oz

This is the behavior that I would expect as only US-ASCII is permitted in HTTP headers.