public java.lang.String getSubnetwork() {
      java.lang.Object ref = subnetwork_;
      if (!(ref instanceof java.lang.String)) {
        com.google.protobuf.ByteString bs = (com.google.protobuf.ByteString) ref;
        java.lang.String s = bs.toStringUtf8();
        subnetwork_ = s;
        return s;
      } else {
        return (java.lang.String) ref;
      }
    }
<pre>
The name of the subnetwork for the TPU node. It must be a preexisting
Google Compute Engine subnetwork. If none is provided, "default" will be
used.
</pre>

<code>string subnetwork = 2;</code>

@return The subnetwork.
java-tpu/proto-google-cloud-tpu-v2alpha1/src/main/java/com/google/cloud/tpu/v2alpha1/NetworkConfig.java