Correct formatting of HttpClientTest comments (#4654)

* Correct formatting of HttpClientTest comments

* add <pre> tags

testing-common/src/main/groovy/io/opentelemetry/instrumentation/test/base/HttpClientTest.groovy

@@ -44,18 +44,27 @@ abstract class HttpClientTest<REQUEST> extends InstrumentationSpecification {
    * this method, such an API should be used and the HTTP status code of the response returned,
    * for example:
    *
+   * <pre>
    * @Override
-   * int sendRequest(Request request, String method, URI uri, Map<String, String headers = [:]) {*   HttpResponse response = client.execute(request)
+   * int sendRequest(Request request, String method, URI uri, Map<String, String headers = [:]) {
+   *   HttpResponse response = client.execute(request)
    *   return response.statusCode()
-   *}*
+   * }
+   * </pre>
+   *
    * If there is no synchronous API available at all, for example as in Vert.X, a CompletableFuture
    * can be used to block on a result, for example:
    *
+   * <pre>
    * @Override
-   * int sendRequest(Request request, String method, URI uri, Map<String, String> headers) {*   CompletableFuture<Integer> future = new CompletableFuture<>(
+   * int sendRequest(Request request, String method, URI uri, Map<String, String> headers) {
-   *   sendRequestWithCallback(request, method, uri, headers) {*     future.complete(it.statusCode())
+   *   CompletableFuture<Integer> future = new CompletableFuture<>(
-   *}*   return future.get()
+   *   sendRequestWithCallback(request, method, uri, headers) {
-   *}
+   *     future.complete(it.statusCode())
+   *   }
+   *   return future.get()
+   * }
+   * </pre>
    */
   abstract int sendRequest(REQUEST request, String method, URI uri, Map<String, String> headers)
 
@@ -67,15 +76,26 @@ abstract class HttpClientTest<REQUEST> extends InstrumentationSpecification {
    * such as ApacheHttpClient's response handler callbacks. This method is used in tests to verify
    * the context is propagated correctly to such callbacks.
    *
+   * <pre>
    * @Override
-   * void sendRequestWithCallback(Request request, String method, URI uri, Map<String, String> headers, RequestResult requestResult) {*   // Hypothetical client accepting a callback
+   * void sendRequestWithCallback(Request request, String method, URI uri, Map<String, String> headers, RequestResult requestResult) {
-   *   client.executeAsync(request) {*     void success(Response response) {*       requestResult.complete(response.statusCode())
+   *   // Hypothetical client accepting a callback
-   *}*     void failure(Throwable throwable) {*       requestResult.complete(throwable)
+   *   client.executeAsync(request) {
-   *}*}*
+   *     void success(Response response) {
+   *       requestResult.complete(response.statusCode())
+   *     }
+   *     void failure(Throwable throwable) {
+   *       requestResult.complete(throwable)
+   *     }
+   *   }
+   *
    *   // Hypothetical client returning a CompletableFuture
    *   client.executeAsync(request).whenComplete { response, throwable ->
    *     requestResult.complete({ response.statusCode() }, throwable)
-   *}*}*
+   *   }
+   * }
+   * </pre>
+   *
    * If the client offers no APIs that accept callbacks, then this method should not be implemented
    * and instead, {@link #testCallback} should be implemented to return false.
    */