In Spring, to verify the user credentials, 'authorization' header is used. Usually, user name and password are encoded using some algorithm(commonly base 64) and passed in this header. But, validating user name and password comes under authentication, does n't it? It means, this 'authorization' header is not appropriate. It should have been called 'authentication' header.
Read https://howtodoinjava.com/spring-boot2/security-rest-basic-auth-example/