In Java 21, of the 2,585 JIRA issues marked as fixed, 1,868 were completed by Oracle, while 717 were contributed by other members of the Java community. Oracle would like to thank the developers working for organizations including Amazon, ARM, Azul, Google, Huawei, IBM, Intel , ISCAS, Red Hat, Rivos, SAP and Tencent for their notable contributions.
O harta cu contributiile la JDK.
Features:
https://openjdk.org/projects/jdk/21/
Download jdk 21:
https://jdk.java.net/21/
eu inca n-am terminat “On Java 8” the Bruce Eckel 
Probabil proiectele greenfield pot folosi ultimele versiuni de java, pe cand cele brownfield folosesc versiuni mai vechi de java, nu se face mereu upgrade la proiectele legacy la ultimele versiuni de java, probabil pot exista probleme de compatibilitate.
Se pot face upgrade-uri, mai ales din considerentele de securitate. Insa, da, trebuie avut grija la compatibilitati cu biblioteci in special
Codul standard java este backwards compatible
