src/main/java/com/passkit/grpc/SingleUseCoupons/Offer.java
public Builder clearCampaignId() {
        
        campaignId_ = getDefaultInstance().getCampaignId();
        onChanged();
        return this;
      }
/**
       * <pre>
       * The campaign id that the offer belongs to (1 campaign can have multiple offers). This field cannot be changed once an offer is linked to a campaign.
       * </pre>
       *
       * <code>string campaignId = 19;</code>
       * @return This builder for chaining.
       */

The campaign id that the offer belongs to (1 campaign can have multiple offers). This field cannot be changed once an offer is linked to a campaign.

string campaignId = 19;
@return This builder for chaining.
The campaign id that the offer belongs to ( 1 campaign can have multiple offers ) . This field cannot be changed once an offer is linked to a campaign . string campaignId = 19 ; @return This builder for chaining .
public Builder clearCampaignId() {
        campaignId_ = getDefaultInstance().getCampaignId();
        onChanged();
        return this;
      }
public Builder clearCampaignId ( ) { campaignId_ = getDefaultInstance ( ) . getCampaignId ( ) ; onChanged ( ) ; return this ; }
<pre>
 The campaign id that the offer belongs to (1 campaign can have multiple offers).
<pre > The campaign id that the offer belongs to ( 1 campaign can have multiple offers ) .