PetStoreClient.java

import software.amazon.awssdk.services.dynamodb.model.AttributeValue;
import software.amazon.awssdk.services.dynamodb.model.PutItemRequest;

....

public String write(final Pet pet) {

  final String id = UUID.randomUUID().toString();
  final PutItemRequest putItemRequest = PutItemRequest.builder()
      .tableName("pet-store")
      .item(
          Map.of(
              "id", AttributeValue.builder().s(id).build(),
              "name", AttributeValue.builder().s(pet.getName()).build(),
              "age", AttributeValue.builder().n(Integer.toString(pet.getAge())).build(),
              "category", AttributeValue.builder().s(pet.getCategory()).build()
          )
      )
      .build();
  dynamoDbClient.putItem(putItemRequest);
  return id;
}