Groovy4, FastStringService, V.206, etc

I noticed in the detailed release notes for V.206 some discussion of Groovy2 vs Groovy4, because apparently at some point in the future Groovy2 may go away and so Groovy4 will be required. There is some info on mitigation, including updating official modules (with its usual issues, IMO) but also updating custom modules. But it looks like the latest collector doesnt force this now, but just supports both Groovy2 and Groovy4. But I want to move on this as soon as I can.

So I did some testing on one of my custom groovy configsources and discovered that when I force the script to use Groovy4 (//!/lib-groovy/v4 on the 1st line) I get one of the errors mentioned in the release notes for V.206 ( https://www.logicmonitor.com/release-notes/v-206-release-notes ). Specifically "Unable to load FastStringService". But unlike some of the other known issues, no workaround or example was given.

import groovy.json.*;
def JsonSlurper jsonSlurper = new JsonSlurper();
def jsonParsed = jsonSlurper.parseText(responseBody)  

The first 2 lines are fine, so I believe there is nothing to be changed with how I'm importing it. The docs I see for latest groovy still show I'd use groovy.json.jsonSlurper. But the 3rd line in the code throws the "Unable to load FastStringService" error.

So I guess I'm just wondering if the community has dealt with this specific issue, or if there is a document that contains a workaround for this case and others. I know LM will be updating their modules, or maybe they already have (I havent looked; their new Modules UI hurts my brain a bit, not looking forward to the old version under settings going away). But updating all our custom code is going to be painful. Somehow I didnt realize this conversion from Groovy2 to Groovy4 was coming, so I'm trying to figure out when that will be a hard line in the sand.

But in the meantime, I'm just wondering if anyone has found a way around this issue? Thanks!