code: @Override
      public RejectTransitGatewayVpcAttachmentResult rejectTransitGatewayVpcAttachment(RejectTransitGatewayVpcAttachmentRequest request) {
          request = beforeClientExecution(request);
          return executeRejectTransitGatewayVpcAttachment(request);
      }
docs: <p>
  Rejects 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>AcceptTransitGatewayVpcAttachment</a> to accept a VPC attachment request.
  </p>
  
  @param rejectTransitGatewayVpcAttachmentRequest
  @return Result of the RejectTransitGatewayVpcAttachment operation returned by the service.
  @sample AmazonEC2.RejectTransitGatewayVpcAttachment
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/ec2-2016-11-15/RejectTransitGatewayVpcAttachment"
  target="_top">AWS API Documentation</a>