The Java language specification is open and there are multiple implementations. OpenJDK is the official open-source reference implementation, and many of the alternative implementations pull from upstream, but OpenJ9 is a different JVM implementation (though does currently use OpenJDK's class libraries to form a complete JDK.)
Before Microsoft opened-up C#, Mono was a completely independent alternative implementation.
Python has CPython (reference open source implementation), but also PyPy, MicroPython and several others.
I'm not sure what you mean when you say the Java spec is open, but Oracle certainly took the position—and the Supreme Court confirmed—that they own copyright in the APIs.
Has Oracle dedicated those to the public domain in the meantime? Or at least licensed them extremely permissively?
More importantly, is there a public body that owns the spec?
>the Supreme Court confirmed—that they own copyright in the APIs.
To use your own terminology, this is clearly and objectively false. The US Supreme Court made no such finding.
What the court concluded was that even if Oracle had a copyright on the API, Google's use of it fell under fair use so that making a ruling on the question of whether the API was protected by copyright was moot.
Your point of order is partially accurate. It was the Federal Circuit that held APIs copyrightable. SCOTUS did not disturb that holding, but did not explicitly affirm it either. However, your contention that this makes copyrightability moot is a stretch.
The majority opinion in Google v Oracle did an involved fair use analysis for the reimplementation of the API that really makes it clear that it's hard for anybody to violate the copyright of an API by doing a clean-room implementation and not have it be covered by fair use.
But who cares if there's a public body who owns the specification? The Supreme Court ruled Google's use of the copyrighted APIs fell within fair use. That gives, within the US (other countries will have other legal circumstances) a basis for anyone to copy pretty much any language so long as they steer clear of the actual copyrighted source code (don't copy MS's C# source code, for instance) and trademark violations.
I don't understand your thought process. You seem to be arguing that whether something has a proprietor is irrelevant to the question of whether it is proprietary. I cannot fathom the kind of reasoning that would lead to such a conclusion.
If the language is owned—by control and by IP—by a single corporation, it is proprietary.
Anyone can implement a compiler or interpreter for C# if they want, and there is a link to the standard for it. Is this clear enough for you?
Also, from an earlier comment you made a false claim and a strange reference.
You claimed that "most of" Java, Rust, C#, Python, and Go have only a single implementation. This is false. There are multiple implementations of each.
Second, you make a bizarre reference to "fad[ing] away like Pascal." Why do you think Pascal faded? I'll give a hint: It had nothing to do with being proprietary. At best that reference is a non sequitur, at worst it demonstrates more confusion on your part.
It isn't my reading comprehension that is deficient. You are talking in circles and demonstrating a remarkable inability to think clearly. I was just being polite.
Something being proprietary means that it is owned. It means "relating to an owner or ownership"; "of, relating to, or characteristic of an owner or title holder"; "used, made, or marketed by one having the exclusive legal right"; "privately owned and managed and run as a profit-making organization."
Before Microsoft opened-up C#, Mono was a completely independent alternative implementation.
Python has CPython (reference open source implementation), but also PyPy, MicroPython and several others.