add app engine feature

Author: diegomarquezp

google-http-client-appengine/src/main/java/com/google/api/client/extensions/appengine/nativeimage/HttpAppEngineFeature.java

@@ -0,0 +1,45 @@
+package com.google.api.client.extensions.appengine.nativeimage;
+
+import com.google.common.collect.ImmutableList;
+import java.util.List;
+import org.graalvm.nativeimage.hosted.Feature;
+import org.graalvm.nativeimage.hosted.RuntimeReflection;
+
+public class HttpAppEngineFeature implements Feature {
+  private static final List<String> APP_ENGINE_CLASSES =
+      ImmutableList.of(
+          "com.google.appengine.api.appidentity.AppIdentityServicePb",
+          "com.google.appengine.api.capabilities.CapabilityServicePb",
+          "com.google.appengine.api.modules.ModulesServicePb");
+
+  private static final List<String> APP_HOSTING_CLASSES =
+      ImmutableList.of(
+          "com.google.apphosting.api.UserServicePb",
+          "com.google.apphosting.api.logservice.LogServicePb");
+
+  @Override
+  public void beforeAnalysis(BeforeAnalysisAccess access) {
+    try {
+      for (String className : APP_ENGINE_CLASSES) {
+        registerClassForReflection(className, access);
+      }
+      for (String className : APP_HOSTING_CLASSES) {
+        registerClassForReflection(className, access);
+      }
+    } catch (Throwable e) {
+      throw new RuntimeException("Error configuring TestFeature", e);
+    }
+  }
+
+  private void registerClassForReflection(
+      String classFullQualifiedName, BeforeAnalysisAccess access) {
+    Class<?> clazz = access.findClassByName(classFullQualifiedName);
+    RuntimeReflection.register(clazz);
+    RuntimeReflection.register(clazz.getDeclaredConstructors());
+    RuntimeReflection.register(clazz.getDeclaredMethods());
+    RuntimeReflection.register(clazz.getDeclaredFields());
+    for (Class<?> subClass : clazz.getInterfaces()) {
+      registerClassForReflection(subClass.getName(), access);
+    }
+  }
+}