docs: data mapper docs (#2900)

data-mapper/src/test/java/com/iluwatar/datamapper/AppTest.java

@@ -36,7 +36,6 @@ final class AppTest {
 
   /**
    * Issue: Add at least one assertion to this test case.
-   *
    * Solution: Inserted assertion to check whether the execution of the main method in {@link App#main(String[])}
    * throws an exception.
    */

data-mapper/src/test/java/com/iluwatar/datamapper/StudentTest.java

@@ -41,7 +41,7 @@ final class StudentTest {
    * @throws Exception if any execution error during test
    */
   @Test
-  void testEquality() throws Exception {
+  void testEquality() {
 
     /* Create some students */
     final var firstStudent = new Student(1, "Adam", 'A');