Document the external WireMock Extension example

Author: oleg-nenashev

README.md

@@ -50,10 +50,8 @@ public class WireMockContainerTest {
 
     @Test
     public void helloWorld() throws Exception {
-        final HttpClient client = HttpClient.newBuilder()
-                .version(HttpClient.Version.HTTP_1_1).build();
-
-        HttpRequest request = HttpRequest.newBuilder()
+        final HttpClient client = HttpClient.newBuilder().build();
+        final HttpRequest request = HttpRequest.newBuilder()
                 .uri(wiremockServer.getRequestURI("hello"))
                 .timeout(Duration.ofSeconds(10))
                 .header("Content-Type", "application/json")
@@ -69,16 +67,101 @@ public class WireMockContainerTest {
 }
 ```
 
-### Using extensions
+### Using WireMock extensions
 
 The API supports adding [WireMock extensions](https://wiremock.org/docs/extending-wiremock/)
 to the test container.
 The extension can be sourced from the classpath for bundled extensions,
 or added from the JAR file in the initializer.
 
-#### Using external extension
+#### Using external extensions
+
+For the external extensions,
+an extension Jar should be pulled to the test directory before running the test.
+[Apache Maven Dependency Plugin](https://maven.apache.org/plugins/maven-dependency-plugin/) can be used for this purpose.
+Make sure that all dependencies of the extension JAR, if any,
+are also included.
+
+Below you can see an examples of using the _JSON Body Transformer_ extension
+from the [9cookies/wiremock-extensions](https://github.com/9cookies/wiremock-extensions).
+
+Copying the dependency:
+
+```xml
+      <plugin>
+        <groupId>org.apache.maven.plugins</groupId>
+        <artifactId>maven-dependency-plugin</artifactId>
+        <version>3.5.0</version>
+        <executions>
+          <execution>
+            <id>copy</id>
+            <phase>package</phase>
+            <goals>
+              <goal>copy</goal>
+            </goals>
+            <configuration>
+              <artifactItems>
+                <artifactItem>
+                  <groupId>com.ninecookies.wiremock.extensions</groupId>
+                  <artifactId>wiremock-extensions</artifactId>
+                  <version>0.4.1</version>
+                  <classifier>jar-with-dependencies</classifier>
+                </artifactItem>
+              </artifactItems>
+              <outputDirectory>${project.build.directory}/test-wiremock-extension</outputDirectory>
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+```
+
+Mapping definition:
+
+```json
+{
+  "request": {
+    "method": "POST",
+    "url": "/json-body-transformer"
+  },
+  "response": {
+    "status": 201,
+    "headers": {
+      "content-type": "application/json"
+    },
+    "jsonBody": {
+      "message": "Hello, $(name)!"
+    },
+    "transformers" : ["json-body-transformer"]
+  }
+}
+```
+
+Test sample:
 
-For the , an extension Jar should be 
+```java
+public class WireMockContainerExtensionTest {
+    @Rule
+    public WireMockContainer wiremockServer = new WireMockContainer("2.35.0")
+            .withMapping("json-body-transformer", WireMockContainerExtensionTest.class, "json-body-transformer.json")
+            .withExtension("JSON Body Transformer", Collections.singleton("com.ninecookies.wiremock.extensions.JsonBodyTransformer"),
+                    Collections.singleton(Paths.get("target", "test-wiremock-extension", "9cookies-wiremock-extensions.jar").toFile()));
+
+    @Test
+    public void testJSONBodyTransformer() throws Exception {
+        final HttpClient client = HttpClient.newBuilder().build();
+        final HttpRequest request = HttpRequest.newBuilder()
+                .uri(wiremockServer.getRequestURI("json-body-transformer"))
+                .timeout(Duration.ofSeconds(10))
+                .header("Content-Type", "application/json")
+                .POST(HttpRequest.BodyPublishers.ofString("{\"name\":\"John Doe\"}")).build();
+
+        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
+
+        assertThat(response.body()).as("Wrong response body")
+                .contains("Hello, John Doe!");
+    }
+}
+```
 
 ## Contributing
 

pom.xml

@@ -123,13 +123,9 @@
                   <artifactId>wiremock-extensions</artifactId>
                   <version>0.4.1</version>
                   <classifier>jar-with-dependencies</classifier>
-                  <overWrite>false</overWrite>
-                  <destFileName>9cookies-wiremock-extensions.jar</destFileName>
                 </artifactItem>
               </artifactItems>
               <outputDirectory>${project.build.directory}/test-wiremock-extension</outputDirectory>
-              <overWriteReleases>false</overWriteReleases>
-              <overWriteSnapshots>true</overWriteSnapshots>
             </configuration>
           </execution>
         </executions>