Refactor the OAuth2 module codebase

[MohamedSabthar]

Description:
Refactor the OAuth2 module codebase with best practices.

• Remove explicit casting and handle errors
• Remove nested if blocks etc.

Describe your problem(s)

Describe your solution(s)

Related Issues (optional):

Suggested Labels (optional):

Suggested Assignees (optional):

[ritikk112]

I would like to work on this issue can you share some more details?

[MohamedSabthar]

👋 Welcome, @ritikk112! 🚀

We're thrilled to have you join the Ballerina Hacktoberfest community! The issue has been assigned to you, and we’re excited to see your contributions.

To help you get started, here are a few essential resources:

1. Connector Contributor Guide: Make sure to go through our Ballerina Hacktoberfest connector contributor guidelines and follow the exact steps, to contribute effectively.
2. Learn Ballerina: Whether you're new to Ballerina or looking to enhance your skills, check out our official learning resources.
3. Community & Support: If you have technical questions, feel free to ask on Stack Overflow with the Ballerina tag, or join us on Discord to connect with other community members.
4. Ballerina Best Practices and Coding Conventions: Coding conventions & Best practices

No contribution is too small, and your feedback is always welcome! Don’t hesitate to ask questions, propose new ideas, or report issues.

Happy coding and welcome aboard! 🎉

[ritikk112]

@MohamedSabthar I've created a PR to fix this here: ballerina-platform/module-ballerina-oauth2#1324 Can you do a quick review on this and lmk if I need to update something in that.

[MohamedSabthar]

@MohamedSabthar I've created a PR to fix this here: ballerina-platform/module-ballerina-oauth2#1324 Can you do a quick review on this and lmk if I need to update something in that.

Hi @ritikk112,

Could you please use the following resources to refactor the Ballerina codebase:

• Coding Conventions
• Best Practices

The current Java codebase already follows the best practices, so it does not require significant changes. The only adjustments needed are to remove nested if blocks. Changes such as replacing null checks with Java optional types or modifying other code blocks are not necessary.

[ritikk112]

I've already added the Java optional types to remove the null checks throughout the codebase and fixed various nested if-else blocks in the recent commit for this repository ,can you do a quick review on it? and if there are some further changes necessary to this repo or any other please let me know.