Mask right curly braces

[cbot59]

How do I put value of such regex? (password)=(.*?(, |$|}]\"))? (java regex, double quote is escaped)

Context:
I'm using MaskingJsonGeneratorDecorator and unable to run the app with above regex.
Here's my current setup

<jsonGeneratorDecorator class="net.logstash.logback.mask.MaskingJsonGeneratorDecorator">
                    <valueMask>
                        <value>(password)=(.*?(, |$|}]"))?</value>
                        <mask>$1=[filtered]$3</mask>
                    </valueMask>
</jsonGeneratorDecorator>

When I debug, the RegexValueMasker stores the Pattern as (.*?(, |$| which is an invalid regex hence lead to an error.
Am I missing something or is it a bug? I tried to escape the } using \, \\, } but none works

Here's my sample input [email protected]}]","thread"
I expect it will be masked into taxPayerPassportNumber=[filtered]}]","thread"

[philsttr]

Seems to be a bug in logback. Filed qos-ch/logback#836