src/vs/workbench/contrib/debug/browser/rawDebugSession.ts/RawDebugSession/completions
class RawDebugSession:	completions(args: DebugProtocol.CompletionsArguments, token: CancellationToken): Promise<DebugProtocol.CompletionsResponse | undefined> {
		if (this.capabilities.supportsCompletionsRequest) {
			return this.send<DebugProtocol.CompletionsResponse>('completions', args, token);
		}
		return Promise.reject(new Error('completions not supported'));
	}