Merge #656

656: Mark internal fields as transient r=curquiza a=axelrindle

# Pull Request

## Related issue
Fixes #655

## What does this PR do?
Gson has issues working with the class `com.meilisearch.sdk.Index` in Java 9 and higher. Specifically all the fields which hold a `com.meilisearch.sdk.HttpClient`. Marking those fields as `transient` excludes them from serialization and thus preventing the reflective access on JDK-internal types.

## PR checklist
Please check if your PR fulfills the following requirements:
- [x] Does this PR fix an existing issue, or have you listed the changes applied in the PR description (and why they are needed)?
- [x] Have you read the contributing guidelines?
- [x] Have you made sure that the title is accurate and descriptive of the changes?

Thank you so much for contributing to Meilisearch!


Co-authored-by: Axel Rindle <mail@axelrindle.de>

src/main/java/com/meilisearch/sdk/Index.java

@@ -19,12 +19,12 @@ public class Index implements Serializable {
     @Getter protected Pagination pagination;
     @Getter protected Faceting faceting;
     @Getter @ToString.Exclude protected String updatedAt;
-    @Getter @ToString.Exclude protected Config config;
-    @ToString.Exclude protected Documents documents;
-    @ToString.Exclude protected TasksHandler tasksHandler;
-    @ToString.Exclude protected Search search;
-    @ToString.Exclude protected SettingsHandler settingsHandler;
-    @ToString.Exclude protected InstanceHandler instanceHandler;
+    @Getter @ToString.Exclude protected transient Config config;
+    @ToString.Exclude protected transient Documents documents;
+    @ToString.Exclude protected transient TasksHandler tasksHandler;
+    @ToString.Exclude protected transient Search search;
+    @ToString.Exclude protected transient SettingsHandler settingsHandler;
+    @ToString.Exclude protected transient InstanceHandler instanceHandler;
 
     /**
      * Sets the Meilisearch configuration for the index

src/test/java/com/meilisearch/integration/ClientTest.java

@@ -1,27 +1,19 @@
 package com.meilisearch.integration;
 
 import static org.hamcrest.MatcherAssert.assertThat;
-import static org.hamcrest.Matchers.arrayWithSize;
-import static org.hamcrest.Matchers.equalTo;
-import static org.hamcrest.Matchers.in;
-import static org.hamcrest.Matchers.instanceOf;
-import static org.hamcrest.Matchers.is;
-import static org.hamcrest.Matchers.nullValue;
+import static org.hamcrest.Matchers.*;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
-import com.google.gson.JsonArray;
-import com.google.gson.JsonObject;
-import com.google.gson.JsonParser;
+import com.google.gson.*;
 import com.meilisearch.integration.classes.AbstractIT;
 import com.meilisearch.integration.classes.TestData;
 import com.meilisearch.sdk.Index;
 import com.meilisearch.sdk.exceptions.MeilisearchApiException;
+import com.meilisearch.sdk.exceptions.MeilisearchException;
 import com.meilisearch.sdk.model.*;
 import com.meilisearch.sdk.utils.Movie;
-import org.junit.jupiter.api.AfterAll;
-import org.junit.jupiter.api.BeforeEach;
-import org.junit.jupiter.api.Tag;
-import org.junit.jupiter.api.Test;
+import java.lang.reflect.Modifier;
+import org.junit.jupiter.api.*;
 
 @Tag("integration")
 public class ClientTest extends AbstractIT {
@@ -304,4 +296,21 @@ public void testCreateDump() throws Exception {
         assertThat(task.getStatus(), is(equalTo(TaskStatus.ENQUEUED)));
         assertThat(dump.getType(), is(equalTo("dumpCreation")));
     }
+
+    /**
+     * Test the exclusion of transient fields.
+     *
+     * @see <a href="https://github.com/meilisearch/meilisearch-java/issues/655">Issue #655</a>
+     */
+    @Test
+    public void testTransientFieldExclusion() throws MeilisearchException {
+        Index test = client.index("Transient");
+
+        Gson gsonWithTransient =
+                new GsonBuilder().excludeFieldsWithModifiers(Modifier.STATIC).create();
+
+        // TODO: Throws StackOverflowError on JDK 1.8, but InaccessibleObjectException on JDK9+
+        Assertions.assertThrows(StackOverflowError.class, () -> gsonWithTransient.toJson(test));
+        Assertions.assertDoesNotThrow(() -> gson.toJson(test));
+    }
 }