fix(Google AI Gemini) — Fixed wrong mapping between function executio…

…n requests and function execution responses. (langchain4j#1802)

Added a test using `AiServices`.
Function execution requests were mapped to function execution responses.

docs/docs/integrations/document-loaders/google-cloud-storage.md

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+---
+sidebar_position: 2
+---
+
+# Google Cloud Storage
+
+A Google Cloud Storage (GCS) document loader that allows you to load documents from storage buckets.
+
+## Maven Dependency
+
+```xml
+<dependency>
+    <groupId>dev.langchain4j</groupId>
+    <artifactId>langchain4j-document-loader-google-cloud-storage</artifactId>
+    <version>0.34.0</version>
+</dependency>
+```
+
+## APIs
+
+- `GoogleCloudStorageDocumentLoader`
+
+## Authentication
+
+The authentication should be handled transparently for you:
+* If your application is running on Google Cloud Platform (Cloud Run, App Engine, Compute Engine, etc)
+* When running locally on your machine, if you are already authenticated via Google's `gcloud` SDK
+
+You should just create a loader specifying just your project ID:
+
+```java
+GoogleCloudStorageDocumentLoader gcsLoader = GoogleCloudStorageDocumentLoader.builder()
+    .project(System.getenv("GCP_PROJECT_ID"))
+    .build();
+```
+
+Otherwise, it's possible to specify `Credentials`, if you have downloaded a service account key, and exported an environment variable pointing to it:
+
+```java
+GoogleCloudStorageDocumentLoader gcsLoader = GoogleCloudStorageDocumentLoader.builder()
+    .project(System.getenv("GCP_PROJECT_ID"))
+    .credentials(GoogleCredentials.fromStream(new FileInputStream(System.getenv("GOOGLE_APPLICATION_CREDENTIALS"))))
+    .build();
+```
+
+Learn more about [credentials](https://cloud.google.com/docs/authentication/application-default-credentials).
+
+When accessing a public bucket, you shouldn't need to authenticate.
+
+## Examples
+
+### Load a single file from a GCS bucket
+
+```java
+GoogleCloudStorageDocumentLoader gcsLoader = GoogleCloudStorageDocumentLoader.builder()
+    .project(System.getenv("GCP_PROJECT_ID"))
+    .build();
+
+Document document = gcsLoader.loadDocument("BUCKET_NAME", "FILE_NAME.txt", new TextDocumentParser());
+```
+
+### Load all files from a GCS bucket
+
+```java
+GoogleCloudStorageDocumentLoader gcsLoader = GoogleCloudStorageDocumentLoader.builder()
+    .project(System.getenv("GCP_PROJECT_ID"))
+    .build();
+
+List<Document> documents = gcsLoader.loadDocuments("BUCKET_NAME", new TextDocumentParser());
+```
+
+### Load all files from a GCS bucket with a glob pattern
+
+```java
+GoogleCloudStorageDocumentLoader gcsLoader = GoogleCloudStorageDocumentLoader.builder()
+    .project(System.getenv("GCP_PROJECT_ID"))
+    .build();
+
+List<Document> documents = gcsLoader.loadDocuments("BUCKET_NAME", "*.txt", new TextDocumentParser());
+```
+
+For more code samples, please have a look at the integration test class:
+- [GoogleCloudStorageDocumentLoaderIT](https://github.com/langchain4j/langchain4j/blob/main/document-loaders/langchain4j-document-loader-google-cloud-storage/src/test/java/dev/langchain4j/data/document/loader/gcs/GoogleCloudStorageDocumentLoaderIT.java)

document-loaders/langchain4j-document-loader-google-cloud-storage/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <parent>
+        <groupId>dev.langchain4j</groupId>
+        <artifactId>langchain4j-parent</artifactId>
+        <version>0.35.0-SNAPSHOT</version>
+        <relativePath>../../langchain4j-parent/pom.xml</relativePath>
+    </parent>
+
+    <artifactId>langchain4j-document-loader-google-cloud-storage</artifactId>
+    <name>LangChain4j :: Document loader :: Google Cloud Storage</name>
+
+    <dependencies>
+
+        <!-- Google Cloud Storage -->
+
+        <dependency>
+            <groupId>com.google.cloud</groupId>
+            <artifactId>google-cloud-storage</artifactId>
+        </dependency>
+
+        <!-- LangChain4j -->
+
+        <dependency>
+            <groupId>dev.langchain4j</groupId>
+            <artifactId>langchain4j-core</artifactId>
+        </dependency>
+
+        <!--- Test dependencies -->
+
+        <dependency>
+            <groupId>dev.langchain4j</groupId>
+            <artifactId>langchain4j</artifactId>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.apache.logging.log4j</groupId>
+            <artifactId>log4j-api</artifactId>
+            <version>2.22.0</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <scope>test</scope>
+        </dependency>
+
+    </dependencies>
+
+    <dependencyManagement>
+        <dependencies>
+            <dependency>
+                <groupId>com.google.cloud</groupId>
+                <artifactId>libraries-bom</artifactId>
+                <scope>import</scope>
+                <type>pom</type>
+                <version>26.46.0</version>
+            </dependency>
+        </dependencies>
+    </dependencyManagement>
+
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-enforcer-plugin</artifactId>
+                <version>3.5.0</version>
+                <executions>
+                    <execution>
+                        <id>enforce</id>
+                        <configuration>
+                            <rules>
+                                <dependencyConvergence/>
+                            </rules>
+                        </configuration>
+                        <goals>
+                            <goal>enforce</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

document-loaders/langchain4j-document-loader-google-cloud-storage/src/main/java/dev/langchain4j/data/document/loader/gcs/GoogleCloudStorageDocumentLoader.java

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+package dev.langchain4j.data.document.loader.gcs;
+
+import com.google.auth.Credentials;
+import com.google.cloud.storage.Blob;
+import com.google.cloud.storage.Storage;
+import com.google.cloud.storage.StorageOptions;
+import com.google.api.gax.paging.Page;
+
+import dev.langchain4j.data.document.Document;
+import dev.langchain4j.data.document.DocumentLoader;
+import dev.langchain4j.data.document.DocumentParser;
+import dev.langchain4j.data.document.source.GcsSource;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static dev.langchain4j.internal.ValidationUtils.ensureNotBlank;
+import static dev.langchain4j.internal.ValidationUtils.ensureNotNull;
+
+/**
+ * Google Cloud Storage Document Loader to load documents from Google Cloud Storage buckets.
+ */
+public class GoogleCloudStorageDocumentLoader {
+
+    private final Storage storage;
+
+    private GoogleCloudStorageDocumentLoader(String project, Credentials credentials) {
+        StorageOptions.Builder storageBuilder = StorageOptions.newBuilder();
+
+        if (project != null) {
+            storageBuilder.setProjectId(ensureNotBlank(project, "project"));
+        }
+
+        if (credentials != null) {
+            storageBuilder.setCredentials(credentials);
+        }
+
+        this.storage = storageBuilder.build().getService();
+    }
+
+    /**
+     * Loads a single document from the specified Google Cloud Storage bucket based on the specified object key.
+     *
+     * @param bucket   GCS bucket to load from.
+     * @param objectName The key of the GCS object which should be loaded.
+     * @param parser   The parser to be used for parsing text from the object.
+     * @return A document containing the content of the GCS object.
+     */
+    public Document loadDocument(String bucket, String objectName, DocumentParser parser) {
+        Blob blob = storage.get(bucket, objectName);
+        if (blob == null) {
+            throw new IllegalArgumentException("Object gs://" + bucket + "/" + objectName + " couldn't be found.");
+        }
+
+        GcsSource gcsSource = new GcsSource(blob);
+        return DocumentLoader.load(gcsSource, ensureNotNull(parser, "parser"));
+    }
+
+    /**
+     * Load a list of documents from the specified bucket, filtered with a glob pattern.
+     *
+     * @param bucket the bucket to load files from
+     * @param globPattern filter only files matching the glob pattern, see https://cloud.google.com/storage/docs/json_api/v1/objects/list#list-object-glob
+     * @param parser the parser to use to parse the document
+     * @return A list of documents from the bucket that match the glob pattern.
+     */
+    public List<Document> loadDocuments(String bucket, String globPattern, DocumentParser parser) {
+        Page<Blob> blobs = globPattern != null ?
+            storage.list(bucket, Storage.BlobListOption.currentDirectory(), Storage.BlobListOption.matchGlob(globPattern)) :
+            storage.list(bucket, Storage.BlobListOption.currentDirectory());
+
+        List<Document> documents = new ArrayList<>();
+
+        for (Blob blob : blobs.iterateAll()) {
+            GcsSource gcsSource = new GcsSource(blob);
+            documents.add(DocumentLoader.load(gcsSource, ensureNotNull(parser, "parser")));
+        }
+
+        return documents;
+    }
+
+    /**
+     * Loads all documents from an GCS bucket.
+     *
+     * @param bucket the bucket to load from.
+     * @param parser The parser to be used for parsing text from the object.
+     * @return A list of documents.
+     */
+    public List<Document> loadDocuments(String bucket, DocumentParser parser) {
+        return loadDocuments(bucket, null, parser);
+    }
+
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    public static class Builder {
+        private String project;
+        private Credentials credentials;
+
+        public Builder project(String project) {
+            this.project = project;
+            return this;
+        }
+
+        public Builder credentials(Credentials credentials) {
+            this.credentials = credentials;
+            return this;
+        }
+
+        public GoogleCloudStorageDocumentLoader build() {
+            return new GoogleCloudStorageDocumentLoader(project, credentials);
+        }
+    }
+}

document-loaders/langchain4j-document-loader-google-cloud-storage/src/main/java/dev/langchain4j/data/document/source/GcsSource.java

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+package dev.langchain4j.data.document.source;
+
+import com.google.cloud.ReadChannel;
+import com.google.cloud.storage.Blob;
+import dev.langchain4j.data.document.DocumentSource;
+import dev.langchain4j.data.document.Metadata;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.channels.Channels;
+
+public class GcsSource implements DocumentSource {
+
+    private final InputStream inputStream;
+    private final Metadata metadata;
+
+    public GcsSource(Blob blob) {
+        this.metadata = getMetadataForBlob(blob);
+        this.inputStream = Channels.newInputStream(blob.reader());
+    }
+
+    @Override
+    public InputStream inputStream() throws IOException {
+        return inputStream;
+    }
+
+    @Override
+    public Metadata metadata() {
+        return metadata;
+    }
+
+    private static Metadata getMetadataForBlob(Blob blob) {
+        Metadata metadata = new Metadata();
+        metadata.put("source", "gs://" + blob.getBucket() + "/" + blob.getName());
+        metadata.put("bucket", blob.getBucket());
+        metadata.put("name", blob.getName());
+        metadata.put("contentType", blob.getContentType());
+        metadata.put("size", blob.getSize());
+        metadata.put("createTime", blob.getCreateTimeOffsetDateTime().toString());
+        metadata.put("updateTime", blob.getUpdateTimeOffsetDateTime().toString());
+        return metadata;
+    }
+}