private void ensureNodeSpecIsMutable() {
        if (!((bitField0_ & 0x00000001) != 0)) {
          nodeSpec_ =
              new java.util.ArrayList<com.google.cloud.tpu.v2.QueuedResource.Tpu.NodeSpec>(
                  nodeSpec_);
          bitField0_ |= 0x00000001;
        }
      }
<pre>
Details of the TPU resource(s) being requested.
</pre>

Protobuf type {@code google.cloud.tpu.v2.QueuedResource.Tpu}
java-tpu/proto-google-cloud-tpu-v2/src/main/java/com/google/cloud/tpu/v2/QueuedResource.java