feat: [OpenAPI] Customize apache request object before invocation

datamodel/openapi/openapi-api-apache-sample/pom.xml

@@ -56,11 +56,31 @@
             <artifactId>wiremock</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.assertj</groupId>
             <artifactId>assertj-core</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.apache.httpcomponents.client5</groupId>
+            <artifactId>httpclient5</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.httpcomponents.core5</groupId>
+            <artifactId>httpcore5</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>io.vavr</groupId>
+            <artifactId>vavr</artifactId>
+            <scope>test</scope>
+        </dependency>
         <dependency>
             <groupId>org.junit.jupiter</groupId>
             <artifactId>junit-jupiter-params</artifactId>
@@ -75,6 +95,11 @@
             <artifactId>jackson-datatype-jsr310</artifactId>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <scope>provided</scope>
+        </dependency>
     </dependencies>
     <build>
         <plugins>

datamodel/openapi/openapi-api-apache-sample/src/test/java/com/sap/cloud/sdk/services/openapi/apache/ApiClientWithRequestCustomizerTest.java

@@ -0,0 +1,91 @@
+package com.sap.cloud.sdk.services.openapi.apache;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.argThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+
+import java.util.function.UnaryOperator;
+
+import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
+import org.apache.hc.core5.http.Header;
+import org.apache.hc.core5.http.io.entity.EntityUtils;
+import org.apache.hc.core5.http.io.support.ClassicRequestBuilder;
+import org.apache.hc.core5.http.protocol.HttpContext;
+import org.junit.jupiter.api.Test;
+
+import com.sap.cloud.sdk.datamodel.openapi.apache.petstore.api.DefaultApi;
+import com.sap.cloud.sdk.services.openapi.apache.apiclient.ApiClient;
+
+import io.vavr.control.Try;
+import lombok.SneakyThrows;
+
+public class ApiClientWithRequestCustomizerTest
+{
+    @Test
+    @SneakyThrows
+    void testRequestCustomizer()
+    {
+        final CloseableHttpClient httpClient = mock(CloseableHttpClient.class);
+
+        // Use the withRequestCustomizer API to add a custom header
+        final UnaryOperator<ClassicRequestBuilder> customizer =
+            builder -> builder.setPath("/custom-path").addHeader("X-Custom", "custom");
+
+        final var apiClient = ApiClient.fromHttpClient(httpClient).withRequestCustomizer(customizer);
+        new DefaultApi(apiClient).findPets();
+
+        verify(httpClient).execute(argThat(req -> Try.run(() -> {
+            assertThat(req.getRequestUri()).isEqualTo("/custom-path");
+            assertThat(req.getMethod()).isEqualTo("GET");
+            assertThat(req.getHeaders()).extracting(Header::getName).containsExactlyInAnyOrder("Accept", "X-Custom");
+            assertThat(req.getFirstHeader("X-Custom").getValue()).isEqualTo("custom");
+            assertThat(req.getFirstHeader("Accept").getValue()).isEqualTo("application/json");
+        }).isSuccess()), any(HttpContext.class), any());
+    }
+
+    @Test
+    @SneakyThrows
+    void testRequestCustomizerWithEntity()
+    {
+        final CloseableHttpClient httpClient = mock(CloseableHttpClient.class);
+
+        final var apiClient = ApiClient.fromHttpClient(httpClient).withRequestCustomizer(b -> b.setEntity("foo"));
+        new DefaultApi(apiClient).findPets();
+
+        verify(httpClient).execute(argThat(req -> Try.run(() -> {
+            assertThat(EntityUtils.toString(req.getEntity())).isEqualTo("foo");
+        }).isSuccess()), any(HttpContext.class), any());
+    }
+
+    @Test
+    @SneakyThrows
+    void testBasicApiCall()
+    {
+        final CloseableHttpClient httpClient = mock(CloseableHttpClient.class);
+
+        final var apiClient = ApiClient.fromHttpClient(httpClient);
+        new DefaultApi(apiClient).findPets();
+
+        verify(httpClient).execute(argThat(req -> Try.run(() -> {
+            assertThat(req.getRequestUri()).isEqualTo("/pets");
+            assertThat(req.getMethod()).isEqualTo("GET");
+            assertThat(req.getFirstHeader("Accept").getValue()).isEqualTo("application/json");
+        }).isSuccess()), any(HttpContext.class), any());
+    }
+
+    @Test
+    @SneakyThrows
+    void testWithBasePath()
+    {
+        final CloseableHttpClient httpClient = mock(CloseableHttpClient.class);
+
+        final var apiClient = ApiClient.fromHttpClient(httpClient).withBasePath("https://api.example.com");
+        new DefaultApi(apiClient).findPets();
+
+        verify(httpClient).execute(argThat(req -> Try.run(() -> {
+            assertThat(req.getUri().toString()).isEqualTo("https://api.example.com/pets");
+        }).isSuccess()), any(HttpContext.class), any());
+    }
+}

datamodel/openapi/openapi-core-apache/src/main/java/com/sap/cloud/sdk/services/openapi/apache/apiclient/ApiClient.java

@@ -1,15 +1,3 @@
-/*
- * Prompt Registry API
- * Prompt Storage service for Design time & Runtime prompt templates.
- *
- * The version of the OpenAPI document: 0.0.1
- *
- *
- * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
- * https://openapi-generator.tech
- * Do not edit the class manually.
- */
-
 package com.sap.cloud.sdk.services.openapi.apache.apiclient;
 
 import static com.sap.cloud.sdk.services.openapi.apache.apiclient.DefaultApiResponseHandler.isJsonMime;
@@ -30,6 +18,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
+import java.util.function.UnaryOperator;
 import java.util.zip.GZIPOutputStream;
 
 import javax.annotation.Nonnull;
@@ -98,13 +87,28 @@ public class ApiClient
     private final String tempFolderPath;
 
     @With( onMethod_ = @Beta )
-    @Nullable
+    @Nonnull
     private final OpenApiResponseListener openApiResponseListener;
 
     // Methods that can have a request body
     private static final Set<Method> BODY_METHODS = Set.of(Method.POST, Method.PUT, Method.PATCH, Method.DELETE);
+
+    // At runtime "localhost" will be replaced as basepath by the Destination's URI.
     private static final String DEFAULT_BASE_PATH = "http://localhost";
 
+    /**
+     * Http request customizer that can be used to manipulate OpenAPI requests before invocation.
+     *
+     * @since 5.28.0
+     */
+    @With( onMethod_ = @Beta )
+    @Nonnull
+    private final UnaryOperator<ClassicRequestBuilder> requestCustomizer;
+
+    private static final OpenApiResponseListener EMPTY_RESPONSE_LISTENER = r -> {
+    };
+    private static final UnaryOperator<ClassicRequestBuilder> EMPTY_REQUEST_CUSTOMIZER = r -> r;
+
     /**
      * Creates an ApiClient instance from an existing HttpClient.
      *
@@ -115,7 +119,13 @@ public class ApiClient
     @Nonnull
     public static ApiClient fromHttpClient( @Nonnull final CloseableHttpClient httpClient )
     {
-        return new ApiClient(httpClient, DEFAULT_BASE_PATH, createDefaultObjectMapper(), null, null);
+        return new ApiClient(
+            httpClient,
+            DEFAULT_BASE_PATH,
+            createDefaultObjectMapper(),
+            null,
+            EMPTY_RESPONSE_LISTENER,
+            EMPTY_REQUEST_CUSTOMIZER);
     }
 
     /**
@@ -130,7 +140,6 @@ public static ApiClient create( @Nonnull final Destination destination )
     {
         return fromHttpClient((CloseableHttpClient) ApacheHttpClient5Accessor.getHttpClient(destination))
             .withBasePath(destination.asHttp().getUri().toString());
-
     }
 
     /**
@@ -184,7 +193,7 @@ public static String parameterToString( @Nullable final Object param )
     {
         if( param == null ) {
             return "";
-        } else if( param instanceof Date date ) {
+        } else if( param instanceof final Date date ) {
             return formatDate(date);
         } else if( param instanceof Collection ) {
             final StringBuilder b = new StringBuilder();
@@ -469,7 +478,66 @@ public <T> T invokeAPI(
         @Nullable final String accept,
         @Nonnull final String contentType,
         @Nonnull final TypeReference<T> returnType )
-        throws OpenApiRequestException
+    {
+        final ClassicRequestBuilder builder =
+            buildClassicRequest(
+                path,
+                method,
+                queryParams,
+                collectionQueryParams,
+                urlQueryDeepObject,
+                body,
+                headerParams,
+                formParams,
+                accept,
+                contentType);
+
+        return invokeAPI(builder, returnType);
+    }
+
+    /**
+     * Invoke API by sending HTTP request with the given request builder.
+     *
+     * @param <T>
+     *            Type
+     * @param requestBuilder
+     *            The request builder with all parameters configured
+     * @param resultType
+     *            Return type
+     * @return The response body
+     * @throws OpenApiRequestException
+     *             API exception
+     */
+    @Nonnull
+    protected <T> T invokeAPI(
+        @Nonnull final ClassicRequestBuilder requestBuilder,
+        @Nonnull final TypeReference<T> resultType )
+    {
+        final ClassicRequestBuilder finalBuilder = requestCustomizer.apply(requestBuilder);
+
+        final HttpClientContext context = HttpClientContext.create();
+        try {
+            final HttpClientResponseHandler<T> responseHandler =
+                new DefaultApiResponseHandler<>(objectMapper, tempFolderPath, resultType, openApiResponseListener);
+            return httpClient.execute(finalBuilder.build(), context, responseHandler);
+        }
+        catch( final IOException e ) {
+            throw new OpenApiRequestException(e);
+        }
+    }
+
+    @Nonnull
+    private ClassicRequestBuilder buildClassicRequest(
+        @Nonnull final String path,
+        @Nonnull final String method,
+        @Nullable final List<Pair> queryParams,
+        @Nullable final List<Pair> collectionQueryParams,
+        @Nullable final String urlQueryDeepObject,
+        @Nullable final Object body,
+        @Nonnull final Map<String, String> headerParams,
+        @Nonnull final Map<String, Object> formParams,
+        @Nullable final String accept,
+        @Nonnull final String contentType )
     {
         if( body != null && !formParams.isEmpty() ) {
             throw new OpenApiRequestException("Cannot have body and form params");
@@ -486,9 +554,6 @@ public <T> T invokeAPI(
         for( final Entry<String, String> keyValue : headerParams.entrySet() ) {
             builder.addHeader(keyValue.getKey(), keyValue.getValue());
         }
-
-        final HttpClientContext context = HttpClientContext.create();
-
         final ContentType contentTypeObj = getContentType(contentType);
         if( body != null || !formParams.isEmpty() ) {
             if( isBodyAllowed(Method.valueOf(method)) ) {
@@ -501,15 +566,7 @@ public <T> T invokeAPI(
             // for empty body
             builder.setEntity(new StringEntity("", contentTypeObj));
         }
-
-        try {
-            final HttpClientResponseHandler<T> responseHandler =
-                new DefaultApiResponseHandler<>(objectMapper, tempFolderPath, returnType, openApiResponseListener);
-            return httpClient.execute(builder.build(), context, responseHandler);
-        }
-        catch( IOException e ) {
-            throw new OpenApiRequestException(e);
-        }
+        return builder;
     }
 
     /**

datamodel/openapi/openapi-core-apache/src/main/java/com/sap/cloud/sdk/services/openapi/apache/apiclient/DefaultApiResponseHandler.java

@@ -69,8 +69,8 @@ class DefaultApiResponseHandler<T> implements HttpClientResponseHandler<T>
     @Nonnull
     private final TypeReference<T> returnType;
 
-    /** Optional listener for OpenAPI response including status code and headers */
-    @Nullable
+    /** Listener for OpenAPI response including status code and headers */
+    @Nonnull
     private final OpenApiResponseListener openApiResponseListener;
 
     @Nullable
@@ -109,9 +109,7 @@ private T processResponse( @Nonnull final ClassicHttpResponse response )
     {
         final int statusCode = response.getCode();
         final Map<String, List<String>> headers = transformResponseHeaders(response.getHeaders());
-        if( openApiResponseListener != null ) {
-            openApiResponseListener.onResponse(new OpenApiResponse(statusCode, headers));
-        }
+        openApiResponseListener.onResponse(new OpenApiResponse(statusCode, headers));
 
         if( statusCode == HttpStatus.SC_NO_CONTENT ) {
             if( returnType.getType().equals(OpenApiResponse.class) ) {