Type: LanguageService

• OS and Version: Mac OS X 10.11.6
• VS Code Version: 1.24.1
• C/C++ Extension Version: 0.17.4

I have some configuration variables that share the same prefix and use '.' as a delimiter. This looks to be standard practice for vscode settings. e.g.
ml.sdk
ml.username
ml.foobar

I'm trying to include some sdk-relative include paths for IntelliSense like this in the workspace folder's settings.json:
"ml.sdk": "/path/to/sdk",
"C_Cpp.default.includePath": [
"${workspaceFolder}/**",
"${config:ml.sdk}/foo",
"${config:ml.sdk}/bar",
],

IntelliSense is unable to locate any of the headers in /path/to/sdk/foo or /path/to/sdk/bar.

If I change the '.' to '_' instead, e.g. ml_sdk, IntelliSense is able to locate the headers.

I have an extension that reads and writes these settings, e.g.
vscode.workspace.getConfiguration('ml').get('sdk');

so I'm not sure I can do that without having a '.' as a settings section-identifier.