public Builder putLabels(java.lang.String key, java.lang.String value) {
      if (key == null) {
        throw new NullPointerException("map key");
      }
      if (value == null) {
        throw new NullPointerException("map value");
      }
      internalGetMutableLabels().getMutableMap().put(key, value);
      bitField0_ |= 0x00000080;
      return this;
    }
<pre>
Labels associated with this workflow.
Labels can contain at most 64 entries. Keys and values can be no longer
than 63 characters and can only contain lowercase letters, numeric
characters, underscores, and dashes. Label keys must start with a letter.
International characters are allowed.
This is a workflow-wide field and is not tied to a specific revision.
</pre>

<code>map&lt;string, string&gt; labels = 8;</code>
java-workflows/proto-google-cloud-workflows-v1/src/main/java/com/google/cloud/workflows/v1/Workflow.java