public Builder setRevisionId(java.lang.String value) {
      if (value == null) {
        throw new NullPointerException();
      }
      revisionId_ = value;
      bitField0_ |= 0x00000002;
      onChanged();
      return this;
    }
<pre>
Optional. The revision of the workflow to retrieve. If the revision_id is
empty, the latest revision is retrieved.
The format is "000001-a4d", where the first six characters define
the zero-padded decimal revision number. They are followed by a hyphen and
three hexadecimal characters.
</pre>

<code>string revision_id = 2 [(.google.api.field_behavior) = OPTIONAL];</code>

@param value The revisionId to set.
@return This builder for chaining.
java-workflows/proto-google-cloud-workflows-v1/src/main/java/com/google/cloud/workflows/v1/GetWorkflowRequest.java