chore: Add a readme

README.md

@@ -0,0 +1,117 @@
+# Extenda Hii Retail GCP Storage client
+A Google Cloud Platform Storage client implemented for JDK 21+ (Virtual threads).
+
+[![Quality Gate Status](https://sonarcloud.io/api/project_badges/measure?project=extenda_hiiretail-gcp-storage-java&metric=alert_status&token=38cd6e4249d32992ab84592be19958602fb47b4d)](https://sonarcloud.io/dashboard?id=extenda_hiiretail-gcp-storage-java)
+[![Coverage](https://sonarcloud.io/api/project_badges/measure?project=extenda_hiiretail-gcp-storage-java&metric=coverage&token=38cd6e4249d32992ab84592be19958602fb47b4d)](https://sonarcloud.io/dashboard?id=extenda_hiiretail-gcp-storage-java)
+[![Code Smells](https://sonarcloud.io/api/project_badges/measure?project=extenda_hiiretail-gcp-storage-java&metric=code_smells&token=38cd6e4249d32992ab84592be19958602fb47b4d)](https://sonarcloud.io/dashboard?id=extenda_hiiretail-gcp-storage-java)
+
+## :nut_and_bolt: Configuration
+
+The library supports changing these settings, via environmental variables:
+
+* `SERVICE_PROJECT_ID`
+
+  The value of your GCP project id. Using `test-project` if not set.
+
+* `STORAGE_EMULATOR_HOST`
+
+  The host url to the emulator. ***Can also be set as system property, e.g. in tests.***
+
+### Docker compose example
+
+```yaml
+services:
+  cloudstorage:
+    image: oittaa/gcp-storage-emulator
+    command: >
+      start
+        --default-bucket=test-bucket
+        --host 0.0.0.0
+        --port 9023
+    environment:
+      STORAGE_DIR: cloudstorage
+    volumes:
+      - ./cloudstorage:/cloudstorage
+    ports:
+      - "9023:9023"
+```
+
+## :notebook_with_decorative_cover: Usage
+
+```xml
+<dependencyManagement>
+  <dependencies>
+    <dependency>
+      <groupId>com.google.cloud</groupId>
+      <artifactId>libraries-bom</artifactId>
+      <version>${version.google-cloud}</version>
+      <type>pom</type>
+      <scope>import</scope>
+    </dependency>
+  </dependencies>
+</dependencyManagement>
+
+<dependencies>
+  <dependency>
+    <groupId>com.google.cloud</groupId>
+    <artifactId>google-cloud-storage</artifactId>
+  </dependency>
+</dependencies>
+```
+
+The library uses `SLF4J` as logging API, so make sure you have `log4j[2]` or `logback` or other
+compatible implementation on the classpath.
+
+## :scroll: Usage
+
+```java
+import com.retailsvc.gcp.pubsub.ObjectToBytesMapper;
+import com.retailsvc.gcp.pubsub.PooledPublisherFactory;
+
+ObjectMapper jsonMapper = new ObjectMapper();
+ObjectToBytesMapper objectMapper = v -> ByteBuffer.wrap(jsonMapper.writeValueAsBytes(v));
+
+PubSubClientFactory factory = new PubSubClientFactory(objectMapper,
+  PooledPublisherFactory.defaultPool());
+
+PubSubClient pubSubClient = factory.create("example.entities.v1");
+
+Object payload = ...
+/*
+ 'payload' could be any of the supported types:
+  - String, such as "{ .. }", "my text" etc.
+  - ByteBuffer
+  - InputStream
+  - Any Jackson serializable type such as Record class, List etc.
+*/
+Map<String, String> attributes = Map.of("Tenant-Id", "...", "key", "value");
+pubSubClient.publish(payload, attributes);
+```
+
+## :wrench: Local development environment
+
+* JDK 21+
+* Python / pre-commit
+
+### Building
+
+```bash
+$ mvn clean package
+```
+
+```bash
+$ mvn verify
+```
+
+#### Install and run the pre-commit hooks before you submit code:
+
+```bash
+$ pre-commit install -t pre-commit -t commit-msg
+```
+
+## :information_desk_person: Contribution
+
+Contributions to the project are welcome, but must adhere to a few guidelines:
+
+ * [Conventional commits](https://www.conventionalcommits.org/en/v1.0.0/) should be followed
+ * Install and use a `editorconfig` plugin to use the project supplied settings