Getting Unmarshall exception while putting data in dynamo db table in spring boot

I am trying to integrate dynamo db to my spring boot application I have been following this [link][1] to implement the dynamo db into my spring boot application ever time I try to put into my table I get this error "Unable to unmarshall exception response with the unmarshallers provided".I have created my dynamo db table manually by using aws console I have mentioned my code below

Controller

    @RestController
public class EmployeeController {
    @Autowired
    private EmployeeRepository employeeRepository;

    @PostMapping("/emp")
    public String data(Employee employee){
        return employeeRepository.updateData(employee);
    }

Service

@Service
public class EmployeeRepository {
    public String updateData(Employee employee) {

        AmazonDynamoDB client = AmazonDynamoDBClientBuilder.standard().build();

        DynamoDB dynamoDB = new DynamoDB(client);

        Table table = dynamoDB.getTable("employee");

        Item item = new Item()
                .withPrimaryKey("employeeId", "1")
                .withString("firstName", "micky")
                .withString("lastName", "mouse")
                .withString("emailId", "mic@gmail.com");
         table.putItem(item);
        return "OK";
    }
}

DynamoDB config

@Configuration
public class DynamoDBConfiguration {
    @Bean
    public DynamoDBMapper dynamoDBMapper(){
        return new DynamoDBMapper(buildAmazonDynamoDb());
    }

    private AmazonDynamoDB buildAmazonDynamoDb() {
        return AmazonDynamoDBClientBuilder
                .standard()
                .withEndpointConfiguration(
                new AwsClientBuilder.EndpointConfiguration("dyno-config")
                )
                .withCredentials(new AWSStaticCredentialsProvider(new BasicAWSCredentials(
                        "accessKey","SecretKey"))).build();
    }
}

Entity

@Data
@AllArgsConstructor
@NoArgsConstructor
@DynamoDBTable(tableName="employee")
public class Employee {
    public String employeeId;
    public String firstName;
    public String lastName;
    public String emailId;
}

The values mentioned in employee entity are of same name as of mu dynamoDB entity.Can anyone help me out what is wrong with my code [1]: https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/JavaDocumentAPIItemCRUD.html