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;
 
   /**

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

@@ -24,6 +24,7 @@
  */
 package com.iluwatar.datamapper;
 
+import java.io.Serial;
 import java.io.Serializable;
 import lombok.AllArgsConstructor;
 import lombok.EqualsAndHashCode;
@@ -41,6 +42,7 @@ import lombok.ToString;
 @AllArgsConstructor
 public final class Student implements Serializable {
 
+  @Serial
   private static final long serialVersionUID = 1L;
 
   @EqualsAndHashCode.Include

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

@@ -27,10 +27,12 @@ package com.iluwatar.datamapper;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
+import lombok.Getter;
 
 /**
  * Implementation of Actions on Students Data.
  */
+@Getter
 public final class StudentDataMapperImpl implements StudentDataMapper {
 
   /* Note: Normally this would be in the form of an actual database */
@@ -70,8 +72,4 @@ public final class StudentDataMapperImpl implements StudentDataMapper {
       throw new DataMapperException("Student [" + name + "] is not found");
     }
   }
-
-  public List<Student> getStudents() {
-    return this.students;
-  }
 }