code: @DoesServiceRequest
      public boolean exists(final AccessCondition accessCondition, FileRequestOptions options, OperationContext opContext)
              throws StorageException {
          return this.exists(false, accessCondition, options, opContext);
      }
docs: Returns a value that indicates whether the directory exists, using the specified request options and operation
  context.
  
  @param accessCondition
  An {@link AccessCondition} object that represents the access conditions for the share.
  @param options
  A {@link FileRequestOptions} object that specifies any additional options for the request. Specifying
  <code>null</code> will use the default request options from the associated service client (
  {@link CloudFileClient}).
  @param opContext
  An {@link OperationContext} object that represents the context for the current operation. This object
  is used to track requests to the storage service, and to provide additional runtime information about
  the operation.
  
  @return <code>true</code> if the directory exists, otherwise <code>false</code>.
  
  @throws StorageException
  If a storage service error occurred.