[Serialization] Reorganize module structure

plugins/kotlinx-serialization/testData/boxIr/generics.kt

@@ -0,0 +1,22 @@
+// IGNORE_BACKEND_FIR: JVM_IR
+// TARGET_BACKEND: JVM_IR
+
+// WITH_STDLIB
+
+import kotlinx.serialization.*
+import kotlinx.serialization.json.*
+
+@Serializable
+data class Foo<T>(val i: Int, val t: T? = null)
+
+@Serializable
+class Holder(val f1: Foo<String>, val f2: Foo<Int>)
+
+fun box(): String {
+    val holder = Holder(Foo(1, "1"), Foo(2))
+    val str = Json.encodeToString(Holder.serializer(), holder)
+    if (str != """{"f1":{"i":1,"t":"1"},"f2":{"i":2}}""") return str
+    val decoded = Json.decodeFromString(Holder.serializer(), str)
+    if (decoded.f1.t != holder.f1.t) return "f1.t: ${decoded.f1.t}"
+    return "OK"
+}