Adjust opt-in required to use string-manipulation functions in Kotlin <= 1.5

Author: smowton

java/kotlin-extractor/src/main/kotlin/KotlinUsesExtractor.kt

@@ -67,7 +67,6 @@ open class KotlinUsesExtractor(
         TypeResult(fakeKotlinType(), "", "")
     )
 
-    @OptIn(kotlin.ExperimentalStdlibApi::class) // Annotation required by kotlin versions < 1.5
     fun extractFileClass(f: IrFile): Label<out DbClass> {
         val pkg = f.fqName.asString()
         val jvmName = getFileClassName(f)

java/kotlin-extractor/src/main/kotlin/utils/ClassNames.kt

@@ -22,6 +22,7 @@ import org.jetbrains.kotlin.load.kotlin.JvmPackagePartSource
 // for `that`.
 private fun getName(d: IrDeclarationWithName) = (d as? IrAnnotationContainer)?.let { getJvmName(it) } ?: d.name.asString()
 
+@OptIn(ExperimentalStdlibApi::class) // Annotation required by kotlin versions < 1.5
 fun getFileClassName(f: IrFile) =
     getJvmName(f) ?:
         ((f.fileEntry.name.replaceFirst(Regex(""".*[/\\]"""), "")