[Serialization] Reorganize module structure

plugins/kotlinx-serialization/testData/firMembers/privatePropertiesSerialization.kt

@@ -0,0 +1,37 @@
+// WITH_STDLIB
+
+/**
+ * write$Self and synthetic constructor are required for correct serialization and deserialization of private fields,
+ * otherwise inaccessible from e.g. Derived.$serializer.serialize().
+ * This test verifies that.
+ */
+import kotlinx.serialization.*
+import kotlinx.serialization.json.*
+
+@Serializable
+open class Parent(private val ctor: Int) {
+    private var body: String = "42"
+
+    fun checkDeser(c: Int, b: String): String {
+        if (this.ctor != c) return "Ctor : ${this.ctor}"
+        if (this.body != b) return "Body : ${this.body}"
+        return "OK"
+    }
+}
+
+@Serializable
+class Derived: Parent(42)
+
+fun test(targetString: String): String {
+    val c = Derived()
+    val j = Json { encodeDefaults = true }
+    val s = j.encodeToString(Derived.serializer(), c)
+    if (s != targetString) return s
+    val d = j.decodeFromString(Derived.serializer(), """{"ctor":43,"body":"43"}""")
+    return d.checkDeser(43, "43")
+    return "OK"
+}
+
+fun box(): String {
+    return test("""{"ctor":42,"body":"42"}""")
+}