mark parameter as deprecated since it is always null

leaving the parameter there seems to have been a mistake,
since it was _was_ removed from nullSafeSet()

hibernate-core/src/main/java/org/hibernate/usertype/UserType.java

@@ -286,8 +286,10 @@ public interface UserType<J> {
 	 * Read an instance of the Java class mapped by this custom type
 	 * from the given JDBC {@link ResultSet}. Implementors must handle
 	 * null column values.
+	 *
+	 * @param owner in Hibernate 6, this is always null
 	 */
-	J nullSafeGet(ResultSet rs, int position, SharedSessionContractImplementor session, Object owner)
+	J nullSafeGet(ResultSet rs, int position, SharedSessionContractImplementor session, @Deprecated Object owner)
 			throws SQLException;
 
 	/**