How to request mapping extras from OCL API?

Received a question from Andrew Moko that I’ll answer here:

I’m currently utilizing the OCL API to retrieve JSON data, and I’ve encountered an issue with the mapping data. It seems that the mapping data does not include the “extras” or custom attributes I expected. I’m wondering if there might be a parameter that I’m overlooking or if this data is not included in the response.

Here’s the URL I’m using to access the data:

You can get at a mapping’s extras in a few ways. The best method depends on what you’re trying to achieve. A couple options: