@java.lang.Override
  public java.lang.String getMetadataOrThrow(java.lang.String key) {
    if (key == null) {
      throw new NullPointerException("map key");
    }
    java.util.Map<java.lang.String, java.lang.String> map = internalGetMetadata().getMap();
    if (!map.containsKey(key)) {
      throw new java.lang.IllegalArgumentException();
    }
    return map.get(key);
  }
<pre>
Custom metadata to apply to the TPU Node.
Can set startup-script and shutdown-script
</pre>

<code>map&lt;string, string&gt; metadata = 34;</code>
java-tpu/proto-google-cloud-tpu-v2alpha1/src/main/java/com/google/cloud/tpu/v2alpha1/Node.java