[LL] Add LL API module for JDK 11 tests to support Lincheck tests

- Lincheck is compiled with JDK 11 and the `low-level-api-fir` module is
  based on the JDK 8 toolchain, so we need to add a new module with a
  JDK 11 toolchain to support Lincheck tests. We cannot bump
  `low-level-api-fir` to JDK 11 because `low-level-api-fir-for-ide`
  requires it to be based on a JDK 8 toolchain.
- Using a Gradle test suite is unfortunately not an option, because
  `low-level-api-fir-for-ide` will think that the whole
  `low-level-api-fir` module is compiled with JDK 11 if just a single
  test suite has this toolchain.

^KT-62136

analysis/build.gradle.kts

@@ -13,6 +13,7 @@ tasks.register("analysisAllTests") {
         ":analysis:analysis-api-fe10:test",
         ":analysis:analysis-api-standalone:test",
         ":analysis:low-level-api-fir:test",
+        ":analysis:low-level-api-fir:tests-jdk11:test",
         ":analysis:symbol-light-classes:test"
     )
 

analysis/low-level-api-fir/tests-jdk11/build.gradle.kts

@@ -0,0 +1,37 @@
+plugins {
+    kotlin("jvm")
+    id("jps-compatible")
+}
+
+dependencies {
+    testImplementation(libs.junit.jupiter.api)
+    testRuntimeOnly(libs.junit.jupiter.engine)
+
+    testImplementation(project(":analysis:analysis-api"))
+    testImplementation(project(":analysis:low-level-api-fir"))
+    testImplementation("org.jetbrains.kotlinx:lincheck:2.23")
+}
+
+sourceSets {
+    "test" { projectDefault() }
+}
+
+configureJvmToolchain(JdkMajorVersion.JDK_11_0)
+
+projectTest(jUnitMode = JUnitMode.JUnit5) {
+    dependsOn(":dist")
+    workingDir = rootDir
+    useJUnitPlatform()
+
+    // This is required by lincheck model checking to be able to use `jdk.internal.misc.Unsafe` and similar classes under the hood.
+    jvmArgs(
+        "--add-opens",
+        "java.base/jdk.internal.misc=ALL-UNNAMED",
+        "--add-exports",
+        "java.base/jdk.internal.util=ALL-UNNAMED",
+        "--add-exports",
+        "java.base/sun.security.action=ALL-UNNAMED"
+    )
+}
+
+testsJar()

analysis/low-level-api-fir/tests-jdk11/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/caches/ExampleLincheckTest.kt

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.analysis.low.level.api.fir.caches
+
+import org.jetbrains.kotlinx.lincheck.annotations.Operation
+import org.jetbrains.kotlinx.lincheck.check
+import org.jetbrains.kotlinx.lincheck.strategy.managed.modelchecking.ModelCheckingOptions
+import org.jetbrains.kotlinx.lincheck.strategy.stress.StressOptions
+import org.junit.jupiter.api.Test
+import java.util.concurrent.atomic.AtomicInteger
+
+// This is an example Lincheck test to ensure that the test infrastructure is working. It will be replaced with proper "cleanable soft value
+// cache" tests in the scope of KT-62136.
+
+class ExampleLincheckTest {
+    private val c = AtomicInteger(0)
+
+    @Operation
+    fun inc(): Int = c.incrementAndGet()
+
+    @Operation
+    fun get(): Int = c.get()
+
+    @Test
+    fun stressTest() = StressOptions().check(this::class)
+
+    @Test
+    fun modelCheckingTest() = ModelCheckingOptions().check(this::class)
+}