src/vs/workbench/api/common/extHostQuickOpen.ts/ExtHostInputBox/validationMessage2
class ExtHostInputBox:		set validationMessage2(validationMessage: string | { content: string; severity: InputBoxValidationSeverity } | undefined) {
			checkProposedApiEnabled(this.extension, 'inputBoxSeverity');
			this._validationMessage2 = validationMessage;
			if (!validationMessage) {
				this.update({ validationMessage: undefined, severity: Severity.Ignore });
			} else if (typeof validationMessage === 'string') {
				this.update({ validationMessage, severity: Severity.Error });
			} else {
				this.update({ validationMessage: validationMessage.content, severity: validationMessage.severity ?? Severity.Error });
			}
		}