@java.lang.Override
  public java.lang.String getLabelsOrThrow(java.lang.String key) {
    if (key == null) {
      throw new NullPointerException("map key");
    }
    java.util.Map<java.lang.String, java.lang.String> map = internalGetLabels().getMap();
    if (!map.containsKey(key)) {
      throw new java.lang.IllegalArgumentException();
    }
    return map.get(key);
  }
<pre>
Optional. Labels as key value pairs. The key and value should contain
characters which are UTF-8 compliant and less than 50 characters.
</pre>

<code>map&lt;string, string&gt; labels = 4 [(.google.api.field_behavior) = OPTIONAL];</code>
java-telcoautomation/proto-google-cloud-telcoautomation-v1/src/main/java/com/google/cloud/telcoautomation/v1/EdgeSlm.java