code: public void setSubnetIds(java.util.Collection<String> subnetIds) {
          if (subnetIds == null) {
              this.subnetIds = null;
              return;
          }
  
          this.subnetIds = new com.amazonaws.internal.SdkInternalList<String>(subnetIds);
      }
docs: <p>
  The IDs of one or more subnets. You can specify only one subnet per Availability Zone. You must specify at least
  one subnet, but we recommend that you specify two subnets for better availability. The transit gateway uses one
  IP address from each specified subnet.
  </p>
  
  @param subnetIds
  The IDs of one or more subnets. You can specify only one subnet per Availability Zone. You must specify at
  least one subnet, but we recommend that you specify two subnets for better availability. The transit
  gateway uses one IP address from each specified subnet.