Improve contributing guide

CONTRIBUTING.md

@@ -1,4 +1,120 @@
-## Project setup
+# Contributing to OpenTelemetry Proto Java
+
+## Introduction
+
+Welcome to the OpenTelemetry Proto Java repository! 🎉
+
+Thank you for considering contributing to this project. Whether you are fixing a bug, adding new features, improving documentation, or reporting an issue, your contributions help enhance the OpenTelemetry ecosystem.
+
+This repository provides Java bindings for OpenTelemetry protocol (OTLP) by generating code from the OpenTelemetry protocol definitions. 
+
+If you have any questions, feel free to ask in the community channels. We’re happy to help! 😊
+
+
+## Pre-requisites
+
+Before getting started, ensure you have the following installed:
+
+* **JDK 11 or higher** – [Install OpenJDK](https://adoptopenjdk.net/)
+* **Gradle** – [Install Gradle](https://gradle.org/install/)
+* **Docker** (optional, for testing)
+
+Additional Notes:
+* Ensure your JAVA_HOME is correctly set.
+* Consider using a Gradle wrapper (`./gradlew`) instead of a system-wide Gradle installation.
+
+## Local Run/Build
+
+### Building the Project
+
+To build the project and generate Java bindings from the OpenTelemetry proto definitions:
+
+```bash
+./gradlew build
+```
+
+By default, the proto definitions will be downloaded from the latest published tag of `opentelemetry-proto-java`. 
+
+If the latest version is, for example, `0.20.0`, the protos will be downloaded from the `v0.20.0` release.
+
+To override this and specify a different version:
+
+```bash
+./gradlew build -Prelease.version.prop=1.0.0
+```
+
+## Testing
+
+To run tests:
+
+```bash
+./gradlew test
+```
+
+To run a specific test:
+
+```bash
+./gradlew test --tests com.example.SomeTest
+```
+
+To generate a coverage report:
+
+```bash
+./gradlew jacocoTestReport
+```
+
+## Contributing Rules
+
+* Ensure new features have appropriate test coverage.
+* Run `./gradlew check` before submitting a PR.
+* Include clear and concise documentation updates if needed.
+
+Check for issues labeled [`good first issue`](https://github.com/open-telemetry/opentelemetry-proto-java/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22) to start contributing.
+
+
+## Further Help
+
+- **Issues**: If you encounter a bug, [open an issue](https://github.com/open-telemetry/opentelemetry-proto-java/issues)
+
+## Troubleshooting Guide
+
+### Common Issues & Fixes
+
+#### Build fails due to missing dependencies
+**Error:** `Could not resolve dependencies`
+
+**Fix:** Run:
+```bash
+./gradlew build --refresh-dependencies
+```
+
+#### Tests failing
+**Error:** `Test XYZ failed`
+
+**Fix:**
+```bash
+./gradlew test --info
+```
+Check logs and rerun the failing test with:
+```bash
+./gradlew test --tests com.example.FailingTest
+```
+
+## Additional Information
+
+### Dependency Updates
+To check for outdated dependencies:
+```bash
+./gradlew dependencyUpdates
+```
+
+### Publishing to Maven Local
+To publish artifacts to your local Maven repository:
+```bash
+./gradlew publishToMavenLocal
+```
+
+### Project setup
 
 The build downloads proto definitions
 from [open-telemetry/opentelemetry-proto](https://github.com/open-telemetry/opentelemetry-proto) and
@@ -19,3 +135,5 @@ with `-Prelease.version.prop`:
 ```shell
 ./gradlew build -Prelease.version.prop=1.0.0
 ```
+
+Thank you for contributing!