private void ensureStopSequencesIsMutable() {
      if (!stopSequences_.isModifiable()) {
        stopSequences_ = new com.google.protobuf.LazyStringArrayList(stopSequences_);
      }
      bitField0_ |= 0x00000020;
    }
<pre>
Optional. The maximum number of output tokens to generate per message.
</pre>

<code>optional int32 max_output_tokens = 5 [(.google.api.field_behavior) = OPTIONAL];</code>

@return This builder for chaining.
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/GenerationConfig.java