diff --git a/diffblue-cover/diffblue-legal-age-web/pom.xml b/diffblue-cover/diffblue-legal-age-web/pom.xml
index 61e7799..1a30651 100644
--- a/diffblue-cover/diffblue-legal-age-web/pom.xml
+++ b/diffblue-cover/diffblue-legal-age-web/pom.xml
@@ -63,8 +63,34 @@
         <dependency>
             <groupId>org.json</groupId>
             <artifactId>json</artifactId>
-            <version>20220924</version>
+            <version>20231013</version>
         </dependency>
     </dependencies>
 
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.openapitools</groupId>
+                <artifactId>openapi-generator-maven-plugin</artifactId>
+                <!-- RELEASE_VERSION -->
+                <version>7.2.0</version>
+                <!-- /RELEASE_VERSION -->
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>generate</goal>
+                        </goals>
+                        <configuration>
+                            <inputSpec>${project.basedir}/src/main/resources/openapi.yaml</inputSpec>
+                            <output>${project.build.directory}/site/openapi</output>
+                            <generatorName>html2</generatorName>
+                            <configOptions>
+                                <allowUnicodeIdentifiers>false</allowUnicodeIdentifiers>
+                            </configOptions>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
 </project>
diff --git a/diffblue-cover/diffblue-legal-age-web/src/bank.yaml b/diffblue-cover/diffblue-legal-age-web/src/bank.yaml
deleted file mode 100644
index 29682b2..0000000
--- a/diffblue-cover/diffblue-legal-age-web/src/bank.yaml
+++ /dev/null
@@ -1,29 +0,0 @@
-openapi: 3.1.0
-info:
-  title: Sample of Bank API
-  description: >-
-    Sample of Bank API with only one end-point
-  version: 1.0.0
-servers:
-  - url: 'http://localhost:8182'
-    description: Local server
-paths:
-  /age:
-    get:
-        summary: Validate that person is legal age
-        description: >-
-            Validate that person is legal age
-        operationId: legalAgeValidator
-        parameters:
-            - name: birthDate
-              in: query
-              description: >-
-                Birth date of person
-              required: true
-              schema:
-                type: string
-                format: date
-        responses:
-            '200':
-                description: >-
-                    Person is legal age
diff --git a/diffblue-cover/diffblue-legal-age-web/src/main/java/diffblue/age/web/AgeResource.java b/diffblue-cover/diffblue-legal-age-web/src/main/java/diffblue/age/web/AgeResource.java
index d8f566a..65c3e62 100644
--- a/diffblue-cover/diffblue-legal-age-web/src/main/java/diffblue/age/web/AgeResource.java
+++ b/diffblue-cover/diffblue-legal-age-web/src/main/java/diffblue/age/web/AgeResource.java
@@ -2,6 +2,7 @@
 
 import diffblue.legalage.LegalAgePredicate;
 
+import org.restlet.data.Status;
 import org.restlet.resource.Get;
 import org.restlet.resource.ServerResource;
 import org.json.JSONObject;
@@ -22,6 +23,7 @@ public String legalAgeValidator() {
             birthday = LocalDate.parse(birthdayString, DateTimeFormatter.ISO_DATE);
         } catch (DateTimeParseException e) {
             response.put("error", "Invalid birthday format. Use yyyy-mm-dd.");
+            setStatus(Status.CLIENT_ERROR_BAD_REQUEST);
             return response.toString();
         }
 
diff --git a/diffblue-cover/diffblue-legal-age-web/src/main/resources/openapi.yaml b/diffblue-cover/diffblue-legal-age-web/src/main/resources/openapi.yaml
new file mode 100644
index 0000000..36bc401
--- /dev/null
+++ b/diffblue-cover/diffblue-legal-age-web/src/main/resources/openapi.yaml
@@ -0,0 +1,75 @@
+openapi: 3.0.0
+info:
+  title: Sample of Bank API
+  description: >-
+    Sample of Bank API with only one end-point
+  version: 1.0.0
+servers:
+  - url: 'http://localhost:8182'
+    description: Local server
+paths:
+  /age:
+    get:
+        summary: Validate that person is legal age
+        description: >-
+          Verifies the person has reached the age of 18 years.
+          It returns a boolean value `true` if the answer is positive.
+
+        operationId: legalAgeValidator
+        parameters:
+            -  $ref: '#/components/parameters/BirthDate'
+        responses:
+            200:
+              $ref: '#/components/responses/LegalAgeResponse'
+            400:
+              $ref: '#/components/responses/ErrorResponse'
+
+components:
+  parameters:
+    BirthDate:
+      name: birthDate
+      in: query
+      description: >-
+        Birth date of person
+      required: true
+      schema:
+        type: string
+        format: date
+        example: 2000-01-01
+  schemas:
+    LegalAgeInfo:
+      type: object
+      properties:
+        message:
+          type: string
+          description: Birthday message and legal age status
+        birthday:
+          type: string
+          format: date
+          description: The birthday in yyyy-mm-dd format
+        isLegalAge:
+          type: boolean
+          description: Indicates if the person is of legal age
+      required:
+        - message
+        - birthday
+        - isLegalAge
+  responses:
+    LegalAgeResponse:
+      description: Legal age validation response
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/LegalAgeInfo'
+    ErrorResponse:
+      description: Error response
+      content:
+        application/json:
+          schema:
+            type: object
+            properties:
+              error:
+                type: string
+                description: Error message
+            required:
+              - error
diff --git a/diffblue-cover/diffblue-legal-age-web/src/rest/legal-age-invalid.http b/diffblue-cover/diffblue-legal-age-web/src/rest/legal-age-invalid.http
new file mode 100644
index 0000000..0959021
--- /dev/null
+++ b/diffblue-cover/diffblue-legal-age-web/src/rest/legal-age-invalid.http
@@ -0,0 +1,13 @@
+###
+
+GET {{host}}/age?birthday=xxx
+
+> {%
+    const data = JSON.parse(response.body.toString());
+    client.test("Returns 400 - Bad Request", function() {
+        client.assert(response.status === 400, "Response status is not 400");
+    });
+    client.test("Error message is correct", function() {
+        client.assert(data.error === "Invalid birthday format. Use yyyy-mm-dd.", "error message is incorrect");
+    });
+%}
diff --git a/pom.xml b/pom.xml
index 574ba6f..71bcf8d 100644
--- a/pom.xml
+++ b/pom.xml
@@ -118,7 +118,7 @@
             <dependency>
                 <groupId>org.mockito</groupId>
                 <artifactId>mockito-core</artifactId>
-                <version>5.4.0</version>
+                <version>5.8.0</version>
                 <scope>test</scope>
             </dependency>
             <dependency>
@@ -139,7 +139,7 @@
             <dependency>
                 <groupId>org.apache.groovy</groupId>
                 <artifactId>groovy</artifactId>
-                <version>4.0.16</version>
+                <version>4.0.17</version>
                 <scope>test</scope>
             </dependency>
             <dependency>
@@ -180,7 +180,7 @@
                 <!-- Testing related plugins -->
                 <plugin>
                     <artifactId>maven-surefire-plugin</artifactId>
-                    <version>3.2.2</version>
+                    <version>3.2.3</version>
                     <configuration>
                         <useFile>false</useFile>
                         <includes>
@@ -200,13 +200,13 @@
                 </plugin>
                 <plugin>
                     <artifactId>maven-failsafe-plugin</artifactId>
-                    <version>3.2.2</version>
+                    <version>3.2.3</version>
                 </plugin>
 
                 <!-- Test report related plugins -->
                 <plugin>
                     <artifactId>maven-surefire-report-plugin</artifactId>
-                    <version>3.2.2</version>
+                    <version>3.2.3</version>
                 </plugin>
 
                 <!-- Plugins to document and inspect -->
@@ -224,7 +224,7 @@
                 </plugin>
                 <plugin>
                     <artifactId>maven-javadoc-plugin</artifactId>
-                    <version>3.6.2</version>
+                    <version>3.6.3</version>
                 </plugin>
                 <plugin>
                     <artifactId>maven-dependency-plugin</artifactId>
@@ -254,7 +254,7 @@
                 <plugin>
                     <groupId>com.github.spotbugs</groupId>
                     <artifactId>spotbugs-maven-plugin</artifactId>
-                    <version>4.8.1.0</version>
+                    <version>4.8.2.0</version>
                 </plugin>
                 <plugin>
                     <groupId>org.apache.maven.plugins</groupId>
@@ -264,7 +264,7 @@
                 <plugin>
                     <groupId>org.owasp</groupId>
                     <artifactId>dependency-check-maven</artifactId>
-                    <version>9.0.2</version>
+                    <version>9.0.7</version>
                     <executions>
                         <execution>
                             <goals>
@@ -278,7 +278,7 @@
                 <plugin>
                     <groupId>com.diffplug.spotless</groupId>
                     <artifactId>spotless-maven-plugin</artifactId>
-                    <version>2.41.0</version>
+                    <version>2.41.1</version>
                     <configuration>
                         <!-- optional: limit format enforcement to just the files changed by this feature branch -->
                         <ratchetFrom>origin/main</ratchetFrom>