adoptopenjdk: add 16.0.0

[cust0dian-old]

Motivation for this change

Java 16 builds are now available

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

[SuperSandro2000]

How can the build increase but the download stays the same?

[cust0dian-old]

@SuperSandro2000 that's what AdoptOpenJDK API responds with:

$ curl -s https://api.adoptopenjdk.net/v2/latestAssets/releases/openjdk13 | jq 'map(select(.os == "linux" and .architecture == "aarch64" and .binary_type == "jdk"))[0]'
{
  "os": "linux",
  "architecture": "aarch64",
  "binary_type": "jdk",
  "openjdk_impl": "hotspot",
  "binary_name": "OpenJDK13U-jdk_aarch64_linux_hotspot_13.0.2_8.tar.gz",
  "binary_link": "https://github.com/AdoptOpenJDK/openjdk13-binaries/releases/download/jdk-13.0.2%2B8/OpenJDK13U-jdk_aarch64_linux_hotspot_13.0.2_8.tar.gz",
  "binary_size": 206018212,
  "checksum_link": "https://github.com/AdoptOpenJDK/openjdk13-binaries/releases/download/jdk-13.0.2%2B8/OpenJDK13U-jdk_aarch64_linux_hotspot_13.0.2_8.tar.gz.sha256.txt",
  "version": "13",
  "version_data": {
    "openjdk_version": "13.0.2+8",
    "semver": "13.0.2+8.1"
  },
  "heap_size": "normal",
  "download_count": 3076,
  "updated_at": "2020-01-21T09:21:39Z",
  "timestamp": "2020-01-21T09:21:39Z",
  "release_name": "jdk-13.0.2+8",
  "release_link": "https://github.com/AdoptOpenJDK/openjdk13-binaries/releases/tag/jdk-13.0.2%2B8"
}

see semver in version_data: that's what is being used in generate-sources.py (I just run generate-sources.py to update sources.json for the reference, didn't edit it manually)

If I were to guess, maybe something changed in AdoptOpenJDK's build process for those versions, but the underlying source and expected output is the same?

[SuperSandro2000]

Maybe. I don't know. It just looked strange and maybe something is broken or not.

[cust0dian-old]

Looks like #113120 landed into master now so updates to Java 8-15 releases are no longer part of this PR (sorry, I didn't notice there was already a PR for those updates), so this PR is purely about adding Java 16 releases now

[taku0]

#116935 is merged. Please update this PR too.

[cust0dian-old]

@taku0 thanks for the heads up, updated this PR to be in line with those changes