NoSuchMethod error from Gradle plugin's KotlinPluginAction when using Kotlin 1.5.20-RC

[aerisnju]

We use KotlinPluginWrapper.kotlinPluginVersion to get the kotlin version in boot gradle plugin as advised in #11711. But the jetbrains developers have removed the property kotlinPluginVersion recently in this change. So if we try to upgrade kotlin to 1.5.20-RC, we will see the error

* Exception is:
java.lang.NoSuchMethodError: 'java.lang.String org.jetbrains.kotlin.gradle.plugin.KotlinPluginWrapper.getKotlinPluginVersion()'
	at org.springframework.boot.gradle.plugin.KotlinPluginAction.execute(KotlinPluginAction.java:36)
	at org.springframework.boot.gradle.plugin.KotlinPluginAction.execute(KotlinPluginAction.java:32)
	at org.springframework.boot.gradle.plugin.SpringBootPlugin.lambda$null$0(SpringBootPlugin.java:126)
	...

which prevents us from upgrading kotlin to 1.5.20-RC. Latest boot release 2.5.1 still has the issue.

[wilkinsona]

Thanks for letting us know. That's an unfortunate breaking change in Kotlin's Gradle plugin. It looks like we may be able to retrieve the version by looking for the project.version in the project.properties file. That's what Kotlin's Gradle Plugin is doing under the covers so it should be safe for us to do the same I think.

[materemias]

@wilkinsona is there a workaround we could utilize until the fix comes?

[wilkinsona]

I can't think of one, unfortunately.

[materemias]

thanks anyways

[wilkinsona]

I've reached out to Jetbrains to see if they can reinstate the accessor or point us to another mechanism to get the version that doesn't require us to read their properties file.

[Tapchicoma]

Method signature in 1.5.20 was changed - now it is an extension function for the Project object. Will it work for you?

[wilkinsona]

No, I don't think so as we don't want to require 1.5.20. We'd like to be able to support any 1.5.x version with the same code.