https://docs.spring.io/spring-boot/reference/features/ssl.html
https://docs.spring.io/spring-boot/reference/io/rest-client.html

https://github.com/spring-projects/spring-boot/tree/main/spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/ssl

server:
  port: 8443
  ssl:
    key-store: ./certs/server-cert.pkcs12
    key-store-type: pkcs12
    key-store-password: <pwd>
    keyAlias: 1
    ...
    trust-store
    ...
    bundle:
      jks:
        <bundle-name>:
          key:
            alias: server
            password: <pwd-val>
          keystore:
            type: pkcs12
            location: ${secrets.server.keyStorePath}
            password: <pwd-val>
          truststore:
            ...
          reloadOnUpdate: true

pem-format - just encoded in base64

2024
https://habr.com/ru/companies/sberbank/articles/870116/
    !
2023
https://spring.io/blog/2023/11/07/ssl-hot-reload-in-spring-boot-3-2-0
https://spring.io/blog/2023/06/07/securing-spring-boot-applications-with-ssl
2021
https://habr.com/ru/post/593507/