Can not use with Java versions newer than 13

[andrewhamon]

I am experimenting with upgrading a mixed-jvm codebase to java 17.

I started by setting --java_language_version=17 and --java_runtime_version=17 in our .bazelrc.

Our Kotlin targets that depend on java targets started failing to coming with

bad_class_file: path/to/some/File.class
  class file has wrong version 61.0, should be 55.0
  Please remove or make sure it appears in the correct subdirectory of the classpath.

We are using a custom Kotlin toolchain, so I tried to set jvm_target = "17". However, the rule impl prevents this:

BUILD:89:20: //:kotlin_toolchain_impl: invalid value in 'jvm_target' attribute: has to be one of '1.6', '1.8', '9', '10', '11', '12' or '13' instead of '17'

Indeed, kotlin_toolchain_impl has an allowlist for options that only goes up to 13:

rules_kotlin/kotlin/internal/toolchains.bzl

Lines 176 to 188 in 772d973

	"jvm_target": attr.string(
	doc = "the -jvm_target flag. This is only tested at 1.8.",
	default = "1.8",
	values = [
	"1.6",
	"1.8",
	"9",
	"10",
	"11",
	"12",
	"13",
	],
	),