code: @Override
      public AcceptTransitGatewayVpcAttachmentResult acceptTransitGatewayVpcAttachment(AcceptTransitGatewayVpcAttachmentRequest request) {
          request = beforeClientExecution(request);
          return executeAcceptTransitGatewayVpcAttachment(request);
      }
docs: <p>
  Accepts a request to attach a VPC to a transit gateway.
  </p>
  <p>
  The VPC attachment must be in the <code>pendingAcceptance</code> state. Use
  <a>DescribeTransitGatewayVpcAttachments</a> to view your pending VPC attachment requests. Use
  <a>RejectTransitGatewayVpcAttachment</a> to reject a VPC attachment request.
  </p>
  
  @param acceptTransitGatewayVpcAttachmentRequest
  @return Result of the AcceptTransitGatewayVpcAttachment operation returned by the service.
  @sample AmazonEC2.AcceptTransitGatewayVpcAttachment
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/ec2-2016-11-15/AcceptTransitGatewayVpcAttachment"
  target="_top">AWS API Documentation</a>