> multiple vendors has always been a thing in Java since the early 2000's.
Early 2000s? There was usually one language version that circulated. We had the blackdown java on debian, whatever version sun hosted (1.3?) and something IBM made which was probably on a password protected ftp site available to corporate clients. And it was like that for years. Now there's like 10 vendors supporting 3-5 different major language versions that change every few months.
First of all, multiple vendors has always been a thing in Java since the early 2000's.
Second, configuring a couple of environment variables isn't that much of a challenge.
Third, all IDEs have an option to use a bundled JVM, and allow for JVM selection per project.
Finally, for applications the modern way is to build the runtime alongside the application, or AOT compilation.