code: @DoesServiceRequest
      public void clear(QueueRequestOptions options, OperationContext opContext) throws StorageException {
          if (opContext == null) {
              opContext = new OperationContext();
          }
  
          opContext.initialize();
          options = QueueRequestOptions.populateAndApplyDefaults(options, this.queueServiceClient);
  
          ExecutionEngine.executeWithRetry(this.queueServiceClient, this, this.clearImpl(options),
                  options.getRetryPolicyFactory(), opContext);
      }
docs: Clears all messages from the queue, using the specified request options and operation context.
  
  @param options
  A {@link QueueRequestOptions} 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 CloudQueueClient}).
  @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.
  
  @throws StorageException
  If a storage service error occurred during the operation.