Update release notes wrt #270

Author: cowtowncoder

ion/src/main/java/com/fasterxml/jackson/dataformat/ion/IonParser.java

@@ -155,6 +155,14 @@ public IonParser(IonReader r, IOContext ctxt, ObjectCodec codec) {
         this(r, IonSystemBuilder.standard().build(), ctxt, codec, IonFactory.DEFAULT_ION_PARSER_FEATURE_FLAGS);
     }
 
+    @Deprecated // in 2.12.3, remove from 2.13
+    IonParser(IonReader r, IonSystem system, IOContext ctxt, ObjectCodec codec) {
+        this(r, system, ctxt, codec, IonFactory.DEFAULT_ION_PARSER_FEATURE_FLAGS);
+    }
+
+    /**
+     * @since 2.13
+     */
     IonParser(IonReader r, IonSystem system, IOContext ctxt, ObjectCodec codec, int ionParserFeatures) {
         this._reader = r;
         this._ioContext = ctxt;

release-notes/CREDITS-2.x

@@ -191,3 +191,9 @@ Fabian Meumertzheim (fmeum@github)
 
 * Contributed #241: (ion) Respect `WRITE_ENUMS_USING_TO_STRING` in `EnumAsIonSymbolSerializer`
  (2.12.2)
+
+Nick (manaigrn-amzn@github)
+
+* Contributed #270: (ion) Ion Polymorphic deserialization in 2.12 breaks wrt use of
+  Native Type Ids when upgrading from 2.8
+ (2.12.3)

release-notes/VERSION-2.x

@@ -30,9 +30,12 @@ Modules:
  (reported by Fabian M)
 #268: (smile) Handle sequence of Smile header markers without recursion
  (reported by Fabian M)
-#269: CBOR loses `Map` entries with specific `long` Map key values (32-bit boundary)
+#269: (cbor) CBOR loses `Map` entries with specific `long` Map key values (32-bit boundary)
  (reported by Quantum64@github)
-
+#270: (ion) Ion Polymorphic deserialization in 2.12 breaks wrt use of Native Type Ids
+  when upgrading from 2.8
+ (contributed by Nick)
+ 
 2.12.2 (03-Mar-2021)
 
 #236: (cbor) `ArrayIndexOutOfBoundsException` in `CBORParser` for invalid UTF-8 String