Builder for 
SearchAdGroupAudience objects.
Example usage:
var audienceBuilder = adGroup.targeting().newUserListBuilder();
var audienceOperation = audienceBuilder
  .withAudienceId(3)              // required
  .withBidModifier(1)             // optional
  .build();                       // add the audience
var audience = audienceOperation.getResult();
  Methods:
  
  build()
  Builds the audience. Returns a 
SearchAdGroupAudienceOperation
that corresponds to the addition of the 
SearchAdGroupAudience.  
Return values:
  
  exclude()
  Builds the excluded audience. Returns an 
SearchAdGroupExcludedAudienceOperation
that corresponds to the addition of the 
SearchAdGroupExcludedAudience.
Use of this method while also setting a bid modifier is not supported.  
Return values:
  
  withAudience(userList)
  Sets the user list of the audience.  
Arguments:
  
    | Name | Type | Description | 
    
      | userList | 
      AdsApp.UserList | 
      The user list of the audience. | 
    
  
  Return values:
  
  withAudienceId(audienceId)
  Sets the audience ID of the audience. This field is required. User List IDs
(List IDs) are available on the details page of a User List (found under
the Audiences section of the Shared Library).  
Arguments:
  
    | Name | Type | Description | 
    
      | audienceId | 
      String | 
      The audience ID of the audience. | 
    
  
  Return values:
  
  withBidModifier(modifier)
  Sets the bid modifier value for this audience to the specified value.
The bid modifier is a multiplier applied to the audience's bids, with an
acceptable range from 0.1 (a 90% decrease) to
10.0 (a 900% increase).
For more information about bid modifiers please see the Google Ads Help
Center article. Use of this method when adding an excluded audience is
not supported.  
Arguments:
  
    | Name | Type | Description | 
    
      | modifier | 
      double | 
      The bid modifier value. | 
    
  
  Return values: