SI-10075 annotations go to lazy val's underlying field

This likely regressed in #5294.

Review feedback from retronym:
 - Tie annotation triaging a bit closer together

durban kindly provided initial version of test/files/run/t10075.scala
And pointed out you must force `lazy val`, since `null`-valued field
is serializable regardless of its type.

Test test/files/run/t10075b courtesy of retronym

1 files changed, 35 insertions, 0 deletions

diff --git a/test/files/run/t10075.scala b/test/files/run/t10075.scala
new file mode 100644
index 0000000000..e7564c5c8b
--- /dev/null
+++ b/test/files/run/t10075.scala
@@ -0,0 +1,35 @@
+class NotSerializable
+
+trait SerializableActually {
+  @transient
+  lazy val notSerializedTLV: NotSerializable = new NotSerializable
+
+  @transient
+  val notSerializedTL: NotSerializable = new NotSerializable
+
+  @transient
+  var notSerializedTR: NotSerializable = new NotSerializable
+}
+
+class SerializableBecauseTransient extends Serializable with SerializableActually {
+  @transient
+  lazy val notSerializedLV: NotSerializable = new NotSerializable
+
+  @transient
+  val notSerializedL: NotSerializable = new NotSerializable
+
+  @transient
+  var notSerializedR: NotSerializable = new NotSerializable
+}
+
+// Indirectly check that the @transient annotation on `notSerialized` made it to the underyling field in bytecode.
+// If it doesn't, `writeObject` will fail to serialize the field `notSerialized`, because `NotSerializable` is not serializable
+object Test {
+  def main(args: Array[String]): Unit = {
+    val obj = new SerializableBecauseTransient
+    // must force, since `null` valued field is serialized regardless of its type
+    val forceTLV = obj.notSerializedTLV
+    val forceLV  = obj.notSerializedLV
+    new java.io.ObjectOutputStream(new java.io.ByteArrayOutputStream) writeObject obj
+  }
+}