public Builder mergeServiceAccount(com.google.cloud.tpu.v2.ServiceAccount value) {
      if (serviceAccountBuilder_ == null) {
        if (((bitField0_ & 0x00000200) != 0)
            && serviceAccount_ != null
            && serviceAccount_ != com.google.cloud.tpu.v2.ServiceAccount.getDefaultInstance()) {
          getServiceAccountBuilder().mergeFrom(value);
        } else {
          serviceAccount_ = value;
        }
      } else {
        serviceAccountBuilder_.mergeFrom(value);
      }
      if (serviceAccount_ != null) {
        bitField0_ |= 0x00000200;
        onChanged();
      }
      return this;
    }
<pre>
The Google Cloud Platform Service Account to be used by the TPU node VMs.
If None is specified, the default compute service account will be used.
</pre>

<code>.google.cloud.tpu.v2.ServiceAccount service_account = 37;</code>
java-tpu/proto-google-cloud-tpu-v2/src/main/java/com/google/cloud/tpu/v2/Node.java