code: @Override
      public AddCacheResult addCache(AddCacheRequest request) {
          request = beforeClientExecution(request);
          return executeAddCache(request);
      }
docs: <p>
  Configures one or more gateway local disks as cache for a gateway. This operation is only supported in the cached
  volume, tape and file gateway type (see <a
  href="https://docs.aws.amazon.com/storagegateway/latest/userguide/StorageGatewayConcepts.html">Storage Gateway
  Concepts</a>).
  </p>
  <p>
  In the request, you specify the gateway Amazon Resource Name (ARN) to which you want to add cache, and one or
  more disk IDs that you want to configure as cache.
  </p>
  
  @param addCacheRequest
  @return Result of the AddCache operation returned by the service.
  @throws InvalidGatewayRequestException
  An exception occurred because an invalid gateway request was issued to the service. For more information,
  see the error and message fields.
  @throws InternalServerErrorException
  An internal server error has occurred during the request. For more information, see the error and message
  fields.
  @sample AWSStorageGateway.AddCache
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/storagegateway-2013-06-30/AddCache" target="_top">AWS API
  Documentation</a>