chore: add multi release jar util

plugins/src/main/kotlin/tasks/MultiReleaseJar.kt

@@ -0,0 +1,77 @@
+package tasks
+
+import java.util.*
+import org.gradle.api.Project
+import org.gradle.api.file.FileCollection
+import org.gradle.api.tasks.SourceSetContainer
+import org.gradle.api.tasks.compile.JavaCompile
+import org.gradle.jvm.toolchain.JavaLanguageVersion
+import org.gradle.jvm.toolchain.JavaToolchainService
+import org.gradle.kotlin.dsl.get
+import org.gradle.process.CommandLineArgumentProvider
+import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinJvmCompilation
+
+private val Project.sourceSets: SourceSetContainer
+  get() = this.extensions.getByName("sourceSets") as SourceSetContainer
+
+private val Project.javaToolchains: JavaToolchainService
+  get() = this.extensions.getByName("javaToolchains") as JavaToolchainService
+
+/**
+ * Setup tasks to compile `module-info.java` file for a module named [moduleName] from a source set
+ * with name [sourceSetName] using Java toolchain with version [toolchainVersion].
+ *
+ * It is assumed that source set with [sourceSetName] only extends main JVM source set.
+ * [parentCompilation] represent a compilation corresponding to such a main source set.
+ *
+ * For more details, check this [kotlinx-io](https://github.com/Kotlin/kotlinx-io/pull/406/files) PR
+ */
+public fun Project.configureJava9ModuleInfoCompilation(
+    sourceSetName: String,
+    toolchainVersion: JavaLanguageVersion,
+    parentCompilation: KotlinJvmCompilation,
+    moduleName: String
+) {
+  val moduleOutputs = listOf(parentCompilation.output.allOutputs)
+  val compileClasspathConfiguration =
+      parentCompilation.configurations.compileDependencyConfiguration
+  val sourceSetNameCapitalized =
+      sourceSetName.replaceFirstChar { it.titlecase(Locale.getDefault()) }
+  val javaCompileClasspath = configurations["${sourceSetName}CompileClasspath"]
+  javaCompileClasspath.extendsFrom(compileClasspathConfiguration)
+
+  tasks.named("compile${sourceSetNameCapitalized}Java", JavaCompile::class.java) {
+    dependsOn(moduleOutputs)
+
+    targetCompatibility = "9"
+    sourceCompatibility = "9"
+
+    javaCompiler.set(javaToolchains.compilerFor { languageVersion.set(toolchainVersion) })
+
+    val javaSourceSet = sourceSets[sourceSetName].java
+    destinationDirectory.set(
+        javaSourceSet.destinationDirectory.asFile.get().resolve("META-INF/versions/9"))
+    options.sourcepath = files(javaSourceSet.srcDirs)
+    val moduleFiles = objects.fileCollection().from(moduleOutputs)
+    val modulePath = javaCompileClasspath.filter { it !in moduleFiles.files }
+    dependsOn(modulePath)
+    classpath = objects.fileCollection().from()
+    options.compilerArgumentProviders.add(
+        JigsawArgumentsProvider(moduleName, moduleFiles, modulePath))
+  }
+}
+
+private class JigsawArgumentsProvider(
+    private val moduleName: String,
+    private val moduleFiles: FileCollection,
+    private val modulePath: FileCollection
+) : CommandLineArgumentProvider {
+  override fun asArguments(): Iterable<String> =
+      listOf(
+          "--module-path",
+          modulePath.asPath,
+          "--patch-module",
+          "$moduleName=${moduleFiles.asPath}",
+          "--release",
+          "9")
+}