code: @BetaApi
    public final Operation patchSubnetwork(
        ProjectRegionSubnetworkName subnetwork,
        Subnetwork subnetworkResource,
        List<String> fieldMask) {
  
      PatchSubnetworkHttpRequest request =
          PatchSubnetworkHttpRequest.newBuilder()
              .setSubnetwork(subnetwork == null ? null : subnetwork.toString())
              .setSubnetworkResource(subnetworkResource)
              .addAllFieldMask(fieldMask)
              .build();
      return patchSubnetwork(request);
    }
docs: Patches the specified subnetwork with the data included in the request. Only certain fields can
  up updated with a patch request as indicated in the field descriptions. You must specify the
  current fingeprint of the subnetwork resource being patched.
  
  <p>Sample code:
  
  <pre><code>
  try (SubnetworkClient subnetworkClient = SubnetworkClient.create()) {
  ProjectRegionSubnetworkName subnetwork = ProjectRegionSubnetworkName.of("[PROJECT]", "[REGION]", "[SUBNETWORK]");
  Subnetwork subnetworkResource = Subnetwork.newBuilder().build();
  List&lt;String&gt; fieldMask = new ArrayList&lt;&gt;();
  Operation response = subnetworkClient.patchSubnetwork(subnetwork, subnetworkResource, fieldMask);
  }
  </code></pre>
  
  @param subnetwork Name of the Subnetwork resource to patch.
  @param subnetworkResource A Subnetwork resource. (== resource_for beta.subnetworks ==) (==
  resource_for v1.subnetworks ==)
  @param fieldMask The fields that should be serialized (even if they have empty values). If the
  containing message object has a non-null fieldmask, then all the fields in the field mask
  (and only those fields in the field mask) will be serialized. If the containing object does
  not have a fieldmask, then only non-empty fields will be serialized.
  @throws com.google.api.gax.rpc.ApiException if the remote call fails