Mark previous step unstable (Jenkins shared library)

unstableStep.groovy

import org.jenkinsci.plugins.workflow.actions.WarningAction
import org.jenkinsci.plugins.workflow.graph.FlowNode
import org.jenkinsci.plugins.workflow.job.WorkflowRun
import hudson.model.Result

/**
 * Mark previous step unstable, without marking the whole build unstable
 *
 * This can be used to highlight inefficiencies or non-ideal usage of a pipeline, while permitting overall
 * status (e.g. pull request checks) to return green/success. This will highlight the step and stage in
 * Jenkins graph and stage views. E.g. usage:
 *
 *     echo "Using deprecation option ____ in pipeline. Please use ____"
 *     unstableStep()
 *
 * This will show "Using deprecated option..." in the console and as a step in console view, and the step
 * will be marked yellow/unstable, along with the current stage. The overall build will still show success.
 */
void call(String message) {
    WorkflowRun run = currentBuild.rawBuild
    List<FlowNode> nodes = run.getExecution().getCurrentHeads()
    if (nodes.isEmpty()) {
        throw new IllegalStateException("No current heads found")
    }
    FlowNode currentNode = nodes.get(0)
    // Not sure if message adds anything in this context
    //currentNode.addOrReplaceAction(new WarningAction(Result.UNSTABLE).withMessage(message))
    currentNode.addOrReplaceAction(new WarningAction(Result.UNSTABLE))
}