Mind formatting this to meet the style guide:
```
private[spark] val classLoader =
    if (conf.getBoolean("spark.driver.add-dynamic-jars", false)) {
      val loader = new SparkURLClassLoader(Array.empty[URL], this.getClass.getClassLoader)
      Thread.currentThread.setContextClassLoader(loader)
      Some(loader)
    } else {
      None
    }
```
The only hard requirement is adding brackets and linebreaks around the `None`. The linebreak at the beginning I don't think we require... that one's up to you.