docs: public void marshall(DirectConnectGatewayAssociationProposal directConnectGatewayAssociationProposal, ProtocolMarshaller protocolMarshaller) {
  
          if (directConnectGatewayAssociationProposal == null) {
              throw new SdkClientException("Invalid argument passed to marshall(...)");
          }
  
          try {
              protocolMarshaller.marshall(directConnectGatewayAssociationProposal.getProposalId(), PROPOSALID_BINDING);
              protocolMarshaller.marshall(directConnectGatewayAssociationProposal.getDirectConnectGatewayId(), DIRECTCONNECTGATEWAYID_BINDING);
              protocolMarshaller
                      .marshall(directConnectGatewayAssociationProposal.getDirectConnectGatewayOwnerAccount(), DIRECTCONNECTGATEWAYOWNERACCOUNT_BINDING);
              protocolMarshaller.marshall(directConnectGatewayAssociationProposal.getProposalState(), PROPOSALSTATE_BINDING);
              protocolMarshaller.marshall(directConnectGatewayAssociationProposal.getAssociatedGateway(), ASSOCIATEDGATEWAY_BINDING);
              protocolMarshaller.marshall(directConnectGatewayAssociationProposal.getExistingAllowedPrefixesToDirectConnectGateway(),
                      EXISTINGALLOWEDPREFIXESTODIRECTCONNECTGATEWAY_BINDING);
              protocolMarshaller.marshall(directConnectGatewayAssociationProposal.getRequestedAllowedPrefixesToDirectConnectGateway(),
                      REQUESTEDALLOWEDPREFIXESTODIRECTCONNECTGATEWAY_BINDING);
          } catch (Exception e) {
              throw new SdkClientException("Unable to marshall request to JSON: " + e.getMessage(), e);
          }
      }