public Builder mergeBucketList(com.google.cloud.storagebatchoperations.v1.BucketList value) {
      if (bucketListBuilder_ == null) {
        if (sourceCase_ == 19
            && source_
                != com.google.cloud.storagebatchoperations.v1.BucketList.getDefaultInstance()) {
          source_ =
              com.google.cloud.storagebatchoperations.v1.BucketList.newBuilder(
                      (com.google.cloud.storagebatchoperations.v1.BucketList) source_)
                  .mergeFrom(value)
                  .buildPartial();
        } else {
          source_ = value;
        }
        onChanged();
      } else {
        if (sourceCase_ == 19) {
          bucketListBuilder_.mergeFrom(value);
        } else {
          bucketListBuilder_.setMessage(value);
        }
      }
      sourceCase_ = 19;
      return this;
    }
<pre>
Specifies a list of buckets and their objects to be transformed.
</pre>

<code>.google.cloud.storagebatchoperations.v1.BucketList bucket_list = 19;</code>
java-storagebatchoperations/proto-google-cloud-storagebatchoperations-v1/src/main/java/com/google/cloud/storagebatchoperations/v1/Job.java