Minor javadoc addition wrt #244

Author: cowtowncoder

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

@@ -159,6 +159,14 @@ public Version version() {
         return PackageVersion.VERSION;
     }
 
+    /**
+     * Accessor for {@link IonSystem} this parser instance was construted
+     * with
+     *
+     * @return {@link IonSystem} instance
+     *
+     * @since 2.12.2
+     */
     public IonSystem getIonSystem() {
         return _system;
     }