code: public com.google.api.ads.admanager.axis.v201811.UserDomainTargeting getUserDomainSegment() {
          return userDomainSegment;
      }
docs: Gets the userDomainSegment value for this ProductSegmentation.
  
  @return userDomainSegment   * The user domain segmentation. {@link UserDomainTargeting#isTargeted}
  must be {@code true}.
  
  <p>This attribute is optional.