src/vs/workbench/contrib/tasks/browser/terminalTaskSystem.ts/TerminalTaskSystem/collectMatcherVariables
class TerminalTaskSystem:	private collectMatcherVariables(variables: Set<string>, values: Array<string | ProblemMatcher> | undefined): void {
		if (values === undefined || values === null || values.length === 0) {
			return;
		}
		values.forEach((value) => {
			let matcher: ProblemMatcher;
			if (Types.isString(value)) {
				if (value[0] === '$') {
					matcher = ProblemMatcherRegistry.get(value.substring(1));
				} else {
					matcher = ProblemMatcherRegistry.get(value);
				}
			} else {
				matcher = value;
			}
			if (matcher && matcher.filePrefix) {
				this.collectVariables(variables, matcher.filePrefix);
			}
		});
	}