There is a frequent idiom when making plugins Pipeline-compatible that goes something like

EnvVars env;
if (run instanceof AbstractBuild) {
    env = run.getEnvironment(listener);
    env.overrideAll(((AbstractBuild<?,?>) run).getBuildVariables());
} else {
    env = new EnvVars();
}
String whatever = env.expand(this.whatever);

For a traditional build, we wish to allow configuration parameters (for example of a Builder) to be expanded using either the build's global environment, or "build variables" which include parameters, build wrappers, and other stuff. For a Pipeline build, we do not wish to do any expansion whatsoever—the Groovy script should have done any desired expansion before the SimpleBuildStep (for example) even receives its arguments.

To simplify this idiom, we should:

• define a method getEnvironmentForExpansion(TaskListener) in Run which by default just delegates to getEnvironment(TaskListener)
• override it in AbstractBuild to include getBuildVariables()
• define a method of the same name in WorkflowRun which just returns an empty new EnvVars() (later it can be an @Override)
• optimize Util.replaceMacro(String, Map) to return its argument immediately if the map is empty
• search existing plugins for the above idiom and add a TODO comment to simplify them once the baseline is sufficiently new

The revised code should be something as simple as:

String whatever = run.getEnvironmentForExpansion(listener).expand(this.whatever);