src/vs/workbench/services/configurationResolver/common/variableResolver.ts/AbstractVariableResolverService/constructor
class AbstractVariableResolverService:	constructor(_context: IVariableResolveContext, _labelService?: ILabelService, _userHomePromise?: Promise<string>, _envVariablesPromise?: Promise<IProcessEnvironment>) {
		this._context = _context;
		this._labelService = _labelService;
		this._userHomePromise = _userHomePromise;
		if (_envVariablesPromise) {
			this._envVariablesPromise = _envVariablesPromise.then(envVariables => {
				return this.prepareEnv(envVariables);
			});
		}
	}