Is that possible to use Kotlin features with placeholders?

My current task is to improve our CI/CD pipelines with proper versioning. Here are some details:

For example, I have some java project which consists of pom.xml, some sources, dockerfile and etc. If pom.xml <version> field contains SNAPSHOT label (example: 0.0.1-SNAPSHOT), i need to properly define version of docker image which will be builded a few build steps later. So in this case i'd like to split %maven.project.version% variable (which will be filled by maven build step right before) with delimiter "-" and take first element from result. 

But it looks like that placeholder %maven.project.version% becomes "0.0.1-SNAPSHOT" AFTER it executes *.split method, So i do not receive what i want, instead, i receive list with one element: ["0.0.1-SNAPSHOT"].

So here is my question. If i understand this correct, in pipeline, Kotlin functions executed before placeholders change. Is that so? And, if im doing everything right, how could i make what i want?

Here is some examples from my code:

fun versionCheck(mvnProjectVersion: String): String {
    return mvnProjectVersion.split("-")[0]
}

steps {
    maven {
        name = "Java artifact package"
        goals = "clean install"
        //dockerImage = "maven:3.6.3-openjdk-8"
        //dockerPull = true
        runnerArgs = "-X"
        enabled = true
    }

    val mvnProjectVersion = "%maven.project.version%"
    val delimiter = "-"
    val arrayOfPackageVersion = mvnProjectVersion.split(delimiter)

    script {
        scriptContent = """echo %maven.project.version%
            |echo %maven.project.version%
            |echo ${mvnProjectVersion.split("-")}
            |echo ${mvnProjectVersion.split("-")[0]}
            |echo ${"0.0.1-SNAPSHOT".split("-")[0]}
            |echo ${mvnProjectVersion.split(".".toRegex())[0]}
            |echo ${arrayOfPackageVersion}
            |echo ${arrayOfPackageVersion[0]}
            |echo ${versionCheck("%maven.project.version%")}
        """.trimMargin()
        enabled = true
    }
}

In this example there is only one case when i receive what I want, here it is:

echo ${"0.0.1-SNAPSHOT".split("-")[0]}

Here is my stdout from pipeline:

echo 0.0.1-SNAPSHOT

echo 0.0.1-SNAPSHOT

echo [0.0.1-SNAPSHOT]

echo 0.0.1-SNAPSHOT

echo 0.0.1

echo

echo [0.0.1-SNAPSHOT]

echo 0.0.1-SNAPSHOT

echo 0.0.1-SNAPSHOT