added description

README.md

@@ -0,0 +1,26 @@
+# demo-1
+
+Sample Project to show that Spring Framework FieldError logs sensitive data.
+
+## Usage
+
+1. Start the project as spring boot application
+1. Run the following command to send some data that fails validation
+
+    ```
+    curl --request POST \
+      --url http://localhost:8080/payment-cards \
+      --header 'Content-Type: application/json' \
+      --data '{
+    	"id": "4",
+    	"accountNumber": "4444333322221112",
+    	"expirationDate": "2022-12",
+    	"accountHolder": "Jimmy-2 Doe",
+    }'
+    ```
+
+1. Check log file of spring boot application. It will contain the following log event:
+
+    ```
+    2022-08-11 19:35:56.283  WARN 1 --- [nio-8080-exec-2] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.web.bind.MethodArgumentNotValidException: Validation failed for argument [0] in public com.example.demo.domain.PaymentCard com.example.demo.api.CardController.saveCard(com.example.demo.domain.PaymentCard): [Field error in object 'paymentCard' on field 'accountNumber': rejected value [4444333322221112]; codes [CreditCardNumber.paymentCard.accountNumber,CreditCardNumber.accountNumber,CreditCardNumber.java.lang.String,CreditCardNumber]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [paymentCard.accountNumber,accountNumber]; arguments []; default message [accountNumber],false]; default message [invalid credit card number]] ]
+    ```