fix gradle plugin compatibility

build-logic/src/main/kotlin/org/jetbrains/conventions/gradle-plugin.gradle.kts

@@ -4,13 +4,34 @@
 
 package org.jetbrains.conventions
 
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
 plugins {
     id("org.gradle.kotlin.kotlin-dsl")
     id("org.jetbrains.conventions.base-java")
     kotlin("jvm")
     id("org.jetbrains.conventions.publishing-gradle")
 }
 
+// org.gradle.kotlin.kotlin-dsl sets languageVersion and apiVersion to 1.8 by default starting from Gradle 8
+// as we want to be compatible with previous Gradle versions, we need to set it back to 1.4
+// Note: we should do it directly on tasks and not via top-level `kotlin.compilerOptions`
+//       because kotlin-dsl plugin declares them on task level, and so top-level config is overridden
+tasks.withType<KotlinCompile>().configureEach {
+    compilerOptions {
+        languageVersion.set(dokkaBuild.kotlinLanguageLevel)
+        apiVersion.set(dokkaBuild.kotlinLanguageLevel)
+
+        freeCompilerArgs.addAll(
+            // need 1.4 support, otherwise there might be problems
+            // with Gradle 6.x (it's bundling Kotlin 1.4)
+            "-Xsuppress-version-warnings",
+            "-Xjsr305=strict",
+            "-Xskip-metadata-version-check",
+        )
+    }
+}
+
 // Gradle will put its own version of the stdlib in the classpath, so not pull our own we will end up with
 // warnings like 'Runtime JAR files in the classpath should have the same version'
 listOf(