src/vs/workbench/services/languageDetection/browser/languageDetectionSimpleWorker.ts/LanguageDetectionSimpleWorker/getTextForDetection
class LanguageDetectionSimpleWorker:	private getTextForDetection(uri: string): string | undefined {
		const editorModel = this._getModel(uri);
		if (!editorModel) { return; }

		const end = editorModel.positionAt(10000);
		const content = editorModel.getValueInRange({
			startColumn: 1,
			startLineNumber: 1,
			endColumn: end.column,
			endLineNumber: end.lineNumber
		});
		return content;
	}