code: @Implementation
    @Nullable
    protected Object getSystemService(String name) {
      if (removedSystemServices.contains(name)) {
        return null;
      }
      if (!systemServices.containsKey(name)) {
        return directlyOn(
            realContextImpl,
            ShadowContextImpl.CLASS_NAME,
            "getSystemService",
            ClassParameter.from(String.class, name));
      }
      return systemServices.get(name);
    }
docs: Returns the handle to a system-level service by name. If the service is not available in
  Roboletric, or it is set to unavailable in {@link ShadowServiceManager#setServiceAvailability},
  {@code null} will be returned.