[PAGOPA-1446] feat: subscription validation event handling

pom.xml

@@ -34,6 +34,13 @@
             <artifactId>azure-functions-java-library</artifactId>
             <version>${azure.functions.java.library.version}</version>
         </dependency>
+        <!-- https://mvnrepository.com/artifact/com.azure/azure-messaging-eventgrid -->
+        <dependency>
+            <groupId>com.azure</groupId>
+            <artifactId>azure-messaging-eventgrid</artifactId>
+            <version>4.20.1</version>
+        </dependency>
+
 
         <!-- End Azure -->
 

src/main/java/it/gov/pagopa/gpd/upload/BlobEventFunction.java

@@ -0,0 +1,43 @@
+package it.gov.pagopa.gpd.upload;
+
+import com.azure.core.util.BinaryData;
+import com.azure.messaging.eventgrid.EventGridEvent;
+import com.azure.messaging.eventgrid.systemevents.SubscriptionValidationEventData;
+import com.microsoft.azure.functions.*;
+import com.microsoft.azure.functions.annotation.AuthorizationLevel;
+import com.microsoft.azure.functions.annotation.FunctionName;
+import com.microsoft.azure.functions.annotation.HttpTrigger;
+
+import java.util.List;
+import java.util.logging.Level;
+import java.util.logging.Logger;
+
+public class BlobEventFunction {
+
+    @FunctionName("BlobCreatedSubscriber")
+    public HttpResponseMessage run (
+            @HttpTrigger(name = "BlobCreatedSubscriber",
+                    methods = {HttpMethod.POST, HttpMethod.GET},
+                    route = "upload",
+                    authLevel = AuthorizationLevel.ANONYMOUS) HttpRequestMessage request,
+            final ExecutionContext context) {
+        BinaryData events = BinaryData.fromString(String.valueOf(request.getBody()));
+        Logger logger = context.getLogger();
+        logger.log(Level.INFO, () -> "Request body: " + request.getBody());
+        logger.log(Level.INFO, () -> "Events: " + events);
+
+        List<EventGridEvent> eventGridEvents = EventGridEvent.fromString(events.toString());
+
+        for (EventGridEvent eventGridEvent : eventGridEvents) {
+            if(eventGridEvent.getEventType().equals("SubscriptionValidationEventData")){
+                SubscriptionValidationEventData s = SubscriptionValidationEventData.class.cast(eventGridEvent);
+                return request.createResponseBuilder(HttpStatus.OK)
+                               .header("Content-Type", "application/json")
+                               .body(s.getValidationCode())
+                               .build();
+            }
+        }
+        return request.createResponseBuilder(HttpStatus.NOT_FOUND)
+                       .build();
+    }
+}