Fix #5960: deprecate SubTypeValidator

Author: cowtowncoder

release-notes/VERSION

@@ -212,6 +212,7 @@ Versions: 3.x (for earlier see VERSION-2.x)
  (fix by @cowtowncoder, w/ Claude code)
 #5958: `@JsonView` ignored with `@JsonTypeInfo(include = As.EXTERNAL_PROPERTY)`
  (fixed by Omkhar A)
+#5960: Deprecate un-maintained `tools.jackson.databind.jsontype.impl.SubTypeValidator`
 - Remove project-specific Android SDK compatibility level, use shared;
   no change level itself (stillAndroid SDK 34)
 

src/main/java/tools/jackson/databind/deser/BeanDeserializerFactory.java

@@ -1108,6 +1108,7 @@ protected boolean isIgnorableType(DeserializationContext ctxt, BeanPropertyDefin
         return status.booleanValue();
     }
 
+    @SuppressWarnings("deprecation")
     protected void _validateSubType(DeserializationContext ctxt, JavaType type,
             BeanDescription.Supplier beanDescRef)
     {

src/main/java/tools/jackson/databind/jsontype/impl/SubTypeValidator.java

@@ -12,10 +12,14 @@
  * Helper class used to encapsulate rules that determine subtypes that
  * are invalid to use, even with default typing, mostly due to security
  * concerns.
- * Used by <code>BeanDeserializerFactory</code>
+ * Used by {@code BeanDeserializerFactory}.
+ *<p>
+ * HAS NOT BEEN UPDATED OR MAINTAINED SINCE JACKSON 2.10.
  *
  * @since 2.8.11
+ * @deprecated Since 3.2 (un-maintained since 2.10)
  */
+@Deprecated
 public class SubTypeValidator
 {
     protected final static String PREFIX_SPRING = "org.springframework.";