Deprecate SqlXmlObjectMappingHandler

This class is only known to be used in spring-data-jdbc-ext project
which was never upgraded to Spring Framework 5.x and is no longer
actively developed.

Closes gh-11647

spring-jdbc/src/main/java/org/springframework/jdbc/support/xml/SqlXmlObjectMappingHandler.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2019 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -32,7 +32,10 @@ import org.springframework.lang.Nullable;
  * @since 2.5.5
  * @see java.sql.ResultSet#getSQLXML
  * @see java.sql.SQLXML
+ * @deprecated as of Spring Framework 5.1.5 since this class is only known to be used in spring-data-jdbc-ext project
+ * which was never upgraded to Spring Framework 5.x and is no longer actively developed
  */
+@Deprecated
 public interface SqlXmlObjectMappingHandler extends SqlXmlHandler {
 
 	/**