code: public final Operation updateMaster(
        String projectId, String zone, String clusterId, String masterVersion) {
  
      UpdateMasterRequest request =
          UpdateMasterRequest.newBuilder()
              .setProjectId(projectId)
              .setZone(zone)
              .setClusterId(clusterId)
              .setMasterVersion(masterVersion)
              .build();
      return updateMaster(request);
    }
docs: Updates the master for a specific cluster.
  
  <p>Sample code:
  
  <pre><code>
  try (ClusterManagerClient clusterManagerClient = ClusterManagerClient.create()) {
  String projectId = "";
  String zone = "";
  String clusterId = "";
  String masterVersion = "";
  Operation response = clusterManagerClient.updateMaster(projectId, zone, clusterId, masterVersion);
  }
  </code></pre>
  
  @param projectId Deprecated. The Google Developers Console [project ID or project
  number](https://support.google.com/cloud/answer/6158840). This field has been deprecated
  and replaced by the name field.
  @param zone Deprecated. The name of the Google Compute Engine
  [zone](/compute/docs/zones#available) in which the cluster resides. This field has been
  deprecated and replaced by the name field.
  @param clusterId Deprecated. The name of the cluster to upgrade. This field has been deprecated
  and replaced by the name field.
  @param masterVersion The Kubernetes version to change the master to.
  <p>Users may specify either explicit versions offered by Kubernetes Engine or version
  aliases, which have the following behavior:
  <p>- "latest": picks the highest valid Kubernetes version - "1.X": picks the highest valid
  patch+gke.N patch in the 1.X version - "1.X.Y": picks the highest valid gke.N patch in the
  1.X.Y version - "1.X.Y-gke.N": picks an explicit Kubernetes version - "-": picks the
  default Kubernetes version
  @throws com.google.api.gax.rpc.ApiException if the remote call fails