task-provider-sample: how to read custom task attribute value?

[tdjastrzebski]

According to the task-provider guide:

The task definition has two attributes task and file. task is the name of the Rake task and file points to the Rakefile that contains the task. The task property is required, the file property is optional. If the file attribute is omitted, the Rakefile in the root of the workspace folder is used.

It does not seem the file attribute value from tasks.json is actually being used in extension.ts code.
How do I read custom task attribute values defined in tasks.json?
Where/how are they available?
Do I need to parse tasks.json file?

[alexr00]

task and file are defined for VS Code in the package.json of the extension and are used for identifying a task. They are not for modifying a task, they are instead provided by the the extension.

If you want to pass stuff from tasks.json into an extension, that's this issue: microsoft/vscode#58836