create Instance-Id

src/main/java/fr/lernejo/todo/ApplicationIdentifierFilter.java

@@ -0,0 +1,38 @@
+package fr.lernejo.todo;
+
+import jakarta.servlet.*;
+import jakarta.servlet.Filter;
+import jakarta.servlet.http.HttpServletResponse;
+import org.springframework.stereotype.Component;
+import java.io.IOException;
+import java.util.UUID;
+
+@Component
+public class ApplicationIdentifierFilter implements Filter {
+    private final String instanceId;
+
+    public ApplicationIdentifierFilter() {
+        this.instanceId = UUID.randomUUID().toString();
+        //System.out.println("Your UUID is: " + instanceId);
+    }
+
+    @Override
+    public void init(FilterConfig filterConfig) throws ServletException {
+        Filter.super.init(filterConfig);
+    }
+
+    @Override
+    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
+        //HttpServletResponse httpServletResponse = (HttpServletResponse) servletResponse;
+        if (servletResponse instanceof HttpServletResponse httpServletResponse) {
+            httpServletResponse.setHeader(
+                "Instance-Id", instanceId);
+        }
+        filterChain.doFilter(servletRequest, servletResponse);
+    }
+
+    @Override
+    public void destroy() {
+        Filter.super.destroy();
+    }
+}