IncrementalSyncTask. Fix configuration caches storage

seskar/seskar-gradle-plugin/src/main/kotlin/seskar/gradle/plugin/IncrementalSyncTask.ext.kt

@@ -1,30 +1,44 @@
 package seskar.gradle.plugin
 
-import org.gradle.api.Task
 import org.gradle.api.file.Directory
-import org.gradle.api.provider.Provider
+import org.gradle.api.file.DirectoryProperty
+import org.gradle.api.internal.provider.ProviderInternal
 import org.jetbrains.kotlin.gradle.tasks.IncrementalSyncTask
+import kotlin.contracts.ExperimentalContracts
+import kotlin.contracts.contract
 
 private val ORIGINAL_FILE_FILTERS: List<String> =
     GenerationOptions.entries
         .map { "**/*${it.originalSuffix}" }
 
 internal fun IncrementalSyncTask.excludeOriginalSources() {
-    from.setFrom(from.from.map(::withDirectoryFilter))
+    from.setFrom(
+        from.from.transformDirectories {
+            it.asFileTree.matching {
+                exclude(ORIGINAL_FILE_FILTERS)
+            }
+        }
+    )
 }
 
-private fun Task.withDirectoryFilter(
-    source: Any,
-): Any {
-    if (source !is Provider<*>)
-        return source
+private inline fun <R> Iterable<R>.transformDirectories(
+    crossinline transform: (Directory) -> R,
+): List<R> =
+    flatMap {
+        if (!isDirectoryProvider(it))
+            return@flatMap listOf(it)
 
-    return source.map { value ->
-        if (value !is Directory)
-            return@map value
+        @Suppress("UNCHECKED_CAST")
+        it.map { dir -> transform(dir) } as Iterable<R>
+    }
 
-        project.fileTree(value) {
-            exclude(ORIGINAL_FILE_FILTERS)
-        }
+@OptIn(ExperimentalContracts::class)
+private fun isDirectoryProvider(
+    source: Any?,
+): Boolean {
+    contract {
+        returns(true) implies (source is DirectoryProperty)
     }
+
+    return source is ProviderInternal<*> && source.type == Directory::class.java
 }