better dto/entity structure for GET/POST

src/expenses/dto/get-expense.dto.ts

@@ -28,16 +28,16 @@ export class GetExpenseDto {
   @ApiPropertyOptional({
     description: 'Note about expense'
   })
-  note?: string;
+  note: string;
 
   @ApiPropertyOptional({
     description: 'Merchant for the expense'
   })
-  merchant?: Merchant;
+  merchant: Merchant;
 
   @ApiPropertyOptional({
     type: [Tag],
     description: 'List of tags for the expense'
   })
-  tags?: Tag[];
+  tags: Tag[];
 }