doForAllWithCurrentPaging and fun interface for elements in ktor server

ktor/server/src/jvmMain/kotlin/dev/inmo/micro_utils/ktor/server/configurators/ApplicationCachingHeadersConfigurator.kt

@@ -8,7 +8,7 @@ import kotlinx.serialization.Contextual
 data class ApplicationCachingHeadersConfigurator(
     private val elements: List<@Contextual Element>
 ) : KtorApplicationConfigurator {
-    interface Element { operator fun CachingHeaders.Configuration.invoke() }
+    fun interface Element { operator fun CachingHeaders.Configuration.invoke() }
 
     override fun Application.configure() {
         install(CachingHeaders) {

ktor/server/src/jvmMain/kotlin/dev/inmo/micro_utils/ktor/server/configurators/ApplicationRoutingConfigurator.kt

@@ -10,17 +10,18 @@ import kotlinx.serialization.Serializable
 class ApplicationRoutingConfigurator(
     private val elements: List<@Contextual Element>
 ) : KtorApplicationConfigurator {
-    interface Element { operator fun Route.invoke() }
+    fun interface Element { operator fun Route.invoke() }
+    private val rootInstaller = Element {
+        elements.forEach {
+            it.apply { invoke() }
+        }
+    }
 
     override fun Application.configure() {
-        try {
-            feature(Routing)
-        } catch (e: IllegalStateException) {
-            install(Routing) {
-                elements.forEach {
-                    it.apply { invoke() }
-                }
-            }
+        featureOrNull(Routing) ?.apply {
+            rootInstaller.apply { invoke() }
+        } ?: install(Routing) {
+            rootInstaller.apply { invoke() }
         }
     }
 }

ktor/server/src/jvmMain/kotlin/dev/inmo/micro_utils/ktor/server/configurators/ApplicationSessionsConfigurator.kt

@@ -8,7 +8,7 @@ import kotlinx.serialization.Contextual
 class ApplicationSessionsConfigurator(
     private val elements: List<@Contextual Element>
 ) : KtorApplicationConfigurator {
-    interface Element { operator fun Sessions.Configuration.invoke() }
+    fun interface Element { operator fun Sessions.Configuration.invoke() }
 
     override fun Application.configure() {
         install(Sessions) {

ktor/server/src/jvmMain/kotlin/dev/inmo/micro_utils/ktor/server/configurators/StatusPagesConfigurator.kt

@@ -8,7 +8,7 @@ import kotlinx.serialization.Contextual
 class StatusPagesConfigurator(
     private val elements: List<@Contextual Element>
 ) : KtorApplicationConfigurator {
-    interface Element { operator fun StatusPages.Configuration.invoke() }
+    fun interface Element { operator fun StatusPages.Configuration.invoke() }
 
     override fun Application.configure() {
         install(StatusPages) {