[KPM] KotlinExternalModelContainer: Provide ids API

KT-51262
KT-51220

libraries/tools/kotlin-gradle-plugin-idea/src/main/kotlin/org/jetbrains/kotlin/gradle/kpm/KotlinExternalModelContainer.kt

@@ -9,6 +9,7 @@ import org.jetbrains.kotlin.gradle.kpm.idea.InternalKotlinGradlePluginApi
 import java.io.Serializable
 
 abstract class KotlinExternalModelContainer internal constructor() : Serializable {
+    abstract val ids: Set<KotlinExternalModelId<*>>
     abstract operator fun <T : Any> contains(key: KotlinExternalModelKey<T>): Boolean
     abstract operator fun <T : Any> get(key: KotlinExternalModelKey<T>): T?
     fun <T : Any> getOrThrow(key: KotlinExternalModelKey<T>): T = get(key)
@@ -20,6 +21,7 @@ abstract class KotlinExternalModelContainer internal constructor() : Serializabl
     }
 
     object Empty : KotlinExternalModelContainer() {
+        override val ids: Set<KotlinExternalModelId<*>> = emptySet()
         override fun <T : Any> contains(key: KotlinExternalModelKey<T>): Boolean = false
         override fun <T : Any> get(key: KotlinExternalModelKey<T>): T? = null
     }

libraries/tools/kotlin-gradle-plugin-idea/src/main/kotlin/org/jetbrains/kotlin/gradle/kpm/KotlinExternalModelContainerImpl.kt

@@ -11,6 +11,9 @@ import java.io.Serializable
 internal class KotlinMutableExternalModelContainerImpl : KotlinMutableExternalModelContainer(), Serializable {
     private val values = mutableMapOf<KotlinExternalModelKey<*>, Any>()
 
+    override val ids: Set<KotlinExternalModelId<*>>
+        @Synchronized get() = values.keys.map { it.id }.toSet()
+
     @Synchronized
     override fun <T : Any> set(key: KotlinExternalModelKey<T>, value: T) {
         values[key] = value
@@ -47,6 +50,9 @@ private class SerializedKotlinExternalModelContainer(
 
     private val deserializedValues = mutableMapOf<KotlinExternalModelId<*>, Any>()
 
+    override val ids: Set<KotlinExternalModelId<*>>
+        @Synchronized get() = serializedValues.keys + deserializedValues.keys
+
     @Synchronized
     override fun <T : Any> contains(key: KotlinExternalModelKey<T>): Boolean {
         return key.id in deserializedValues || key.id in serializedValues