code: public void setUserDomainSegment(com.google.api.ads.admanager.axis.v201808.UserDomainTargeting userDomainSegment) {
          this.userDomainSegment = userDomainSegment;
      }
docs: Sets the userDomainSegment value for this ProductSegmentation.
  
  @param userDomainSegment   * The user domain segmentation. {@link UserDomainTargeting#isTargeted}
  must be {@code true}.
  
  <p>This attribute is optional.