Build: Add property for internal kotlin repo

build.gradle.kts

@@ -337,13 +337,13 @@ allprojects {
     repositories {
         kotlinBuildLocalRepo(project)
         mirrorRepo?.let(::maven)
-        bootstrapKotlinRepo?.let(::maven)
         jcenter()
         maven(protobufRepo)
         maven(intellijRepo)
         maven("https://dl.bintray.com/kotlin/ktor")
         maven("https://kotlin.bintray.com/kotlin-dependencies")
-        maven(bootstrapKotlinRepo!!.replace("artifacts/content/maven/", "artifacts/content/internal/repo"))
+        bootstrapKotlinRepo?.let(::maven)
+        internalKotlinRepo?.let(::maven)
     }
 
     configureJvmProject(javaHome!!, jvmTarget!!)

buildSrc/src/main/kotlin/Bootstrap.kt

@@ -7,10 +7,14 @@ import org.gradle.kotlin.dsl.*
 var Project.bootstrapKotlinVersion: String
     get() = this.property("bootstrapKotlinVersion") as String
     private set(value) { this.extra["bootstrapKotlinVersion"] = value }
+
 var Project.bootstrapKotlinRepo: String?
     get() = this.property("bootstrapKotlinRepo") as String?
     private set(value) { this.extra["bootstrapKotlinRepo"] = value }
 
+val Project.internalKotlinRepo: String?
+    get() = bootstrapKotlinRepo?.replace("artifacts/content/maven/", "artifacts/content/internal/repo")
+
 fun Project.kotlinBootstrapFrom(defaultSource: BootstrapOption) {
     val customVersion = project.findProperty("bootstrap.kotlin.version") as String?
     val customRepo = project.findProperty("bootstrap.kotlin.repo") as String?