How to escape double quotes in Condition regular expression

[mitchellarends]

Apigee Environment: Cloud

Problem Description:

I was attempting to modify the regular expression on a Condition that was included in the OOTB SOAP pass thru proxy and was unable to use a regular expression that contained a match on the double quote (") character. Whenever I attempted to save the regular expression (which was validated using the Java run time) Apigee would display the following error:

Error in proxy default. Invalid condition: !((request.header.Content-Type ~~ "(text|application)\/(xml|([a-z]*\+xml))(;(\w)*=(\S*))?") or (request.header.Content-Type ~~ "(multipart\/related)[;[ ]*[\w]+=[\S]+]*(;[ ]*type="application\/xop\+xml")[;[ ]*[\w]+=[\S]+]*")) and (request.verb != "GET") in policy Invalid-SOAP. Reason: Unmatched closing ) near index 224

Failing condition:

The condition below caused the failure message shown above in Apigee.

<Condition>!((request.header.Content-Type ~~ "(text|application)\/(xml|([a-z]*\+xml))(;(\w)*=(\S*))?") or (request.header.Content-Type ~~ "(multipart\/related)[;[ ]*[\w]+=[\S]+]*(;[ ]*type="application\/xop\+xml")[;[ ]*[\w]+=[\S]+]*")) and (request.verb != "GET")</Condition>

Working condition:

The condition below worked around the issue and allowed me to successfully save the proxy changes.

<Condition>!((request.header.Content-Type ~~ "(text|application)\/(xml|([a-z]*\+xml))(;(\w)*=(\S*))?") or (request.header.Content-Type ~~ "(multipart\/related)[;[ ]*[\w]+=[\S]+]*(;[ ]*type=(.{1})application\/xop\+xml(.{1}))[;[ ]*[\w]+=[\S]+]*")) and (request.verb != "GET")</Condition>

Is there a way to escape double quote (") characters in regular expressions? I couldn't find the answer looking at the regular expression and/or condition documentation.