code: @BetaApi(
        "The surface for long-running operations is not stable yet and may change in the future.")
    public final OperationFuture<Instance, UpdateInstanceMetadata> partialUpdateInstanceAsync(
        Instance instance, FieldMask updateMask) {
  
      PartialUpdateInstanceRequest request =
          PartialUpdateInstanceRequest.newBuilder()
              .setInstance(instance)
              .setUpdateMask(updateMask)
              .build();
      return partialUpdateInstanceAsync(request);
    }
docs: Partially updates an instance within a project.
  
  <p>Sample code:
  
  <pre><code>
  try (BaseBigtableInstanceAdminClient baseBigtableInstanceAdminClient = BaseBigtableInstanceAdminClient.create()) {
  Instance instance = Instance.newBuilder().build();
  FieldMask updateMask = FieldMask.newBuilder().build();
  Instance response = baseBigtableInstanceAdminClient.partialUpdateInstanceAsync(instance, updateMask).get();
  }
  </code></pre>
  
  @param instance The Instance which will (partially) replace the current value.
  @param updateMask The subset of Instance fields which should be replaced. Must be explicitly
  set.
  @throws com.google.api.gax.rpc.ApiException if the remote call fails