Java is more open than ever. Those random “scary” bullshit posts appear here and there but — OpenJDK is the standard reference implementation, and it has the same license as the Linux kernel. Different vendors give you builds of this same source, with some patches here and there, and they might provide support for their versions. One of these vendors is Oracle, who gives away the freemium OracleJDK. The latest LTS release is free to use with support, until the next one comes along, plus one year. But you would read more about different support services if you would need that - the same stuff is available for linux. In general, you can use any of these builds interchangeably, it doesn’t really matter. Like, intellij will offer you to download basically any of them.

So yeah, Java is insanely popular (top 3 language, among JS and Python, only their orders change depending on sane metrics (not you tiobe)), and is completely free with multiple vendors. Also, it’s pretty bullshit to consider Oracle any worse than other companies - they are the ones who completely opensourced OpenJDK and are responsible for 95+% of all the commits.