Usage of BootJar instead of BootRepackage in Gradle as part of Spring Boot Migration from 1..5.x to 2.x

I am working on Spring Boot migration from 1.5.12 to 2.1.14. We are using Gradle as a build tool, so as part of Spring Boot migration we had to change Gradle from 3.x to 4.x and trying to update the build.gradle as required. In Spring Boot 2.x migration we have to change the following task in build.gradle

task msnServiceBoot(type: BootRepackage, dependsOn:msnJar) {
    println " Executing MsnServiceBoot task"
    mainClassName = 'com.msn.service.MsnApplication'
    customConfiguration = "cloudconfigexclusion"
    withJarTask = msnJar
}

In the above code we have to update BootRepackage to BootJar as per the latest Spring documentation.

The error, I'm getting after changing from BootRepackage to BootJar is customConfiguration is unknown property.

May I know how to make customConfiguration for Spring Boot 2.x with gradle 4.x