docs: data mapper docs (#2900)

data-mapper/src/main/java/com/iluwatar/datamapper/DataMapperException.java

@@ -24,6 +24,8 @@
  */
 package com.iluwatar.datamapper;
 
+import java.io.Serial;
+
 /**
  * Using Runtime Exception for avoiding dependency on implementation exceptions. This helps in
  * decoupling.
@@ -32,6 +34,7 @@ package com.iluwatar.datamapper;
  */
 public final class DataMapperException extends RuntimeException {
 
+  @Serial
   private static final long serialVersionUID = 1L;
 
   /**