code: public static String resolveVar(String var, Run run, TaskListener taskListener) {
          String resolvedVar = var;
          try {
              final EnvVars envVars = run.getEnvironment(taskListener);
              resolvedVar = envVars.expand(var);
          } catch (IOException | InterruptedException e) {
              LOG.warn("Can't resolve variable " + var + " for {}", run, e);
          }
          return resolvedVar;
      }
docs: Resolve on remoting side during execution.
  Because node may have some specific node vars.