@java.lang.Override
    public com.google.cloud.vertexai.api.RagRetrievalConfig.Ranking.RankService getRankService() {
      if (rankingConfigCase_ == 1) {
        return (com.google.cloud.vertexai.api.RagRetrievalConfig.Ranking.RankService)
            rankingConfig_;
      }
      return com.google.cloud.vertexai.api.RagRetrievalConfig.Ranking.RankService
          .getDefaultInstance();
    }
<pre>
Optional. Config for Rank Service.
</pre>

<code>
.google.cloud.vertexai.v1.RagRetrievalConfig.Ranking.RankService rank_service = 1 [(.google.api.field_behavior) = OPTIONAL];
</code>

@return The rankService.
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/RagRetrievalConfig.java