add nanopb (manual)

components/spotify/cspot/bell/nanopb/tests/oneof/oneof.proto

@@ -0,0 +1,32 @@
+syntax = "proto2";
+
+import 'nanopb.proto';
+
+message SubMessage
+{
+    repeated int32 array = 1 [(nanopb).max_count = 8];
+}
+
+/* Oneof in a message with other fields */
+message OneOfMessage
+{
+    required int32 prefix = 1;
+    oneof values
+    {
+        int32 first = 5;
+        string second = 6 [(nanopb).max_size = 8];
+        SubMessage third = 7;
+    }
+    required int32 suffix = 99;
+}
+
+/* Oneof in a message by itself */
+message PlainOneOfMessage
+{
+    oneof values
+    {
+        int32 first = 5;
+        string second = 6 [(nanopb).max_size = 8];
+        SubMessage third = 7;
+    }
+}