@java.lang.Override
  public Builder toBuilder() {
    return this == DEFAULT_INSTANCE ? new Builder() : new Builder().mergeFrom(this);
  }
<pre>
Required. The function response in JSON object format.
Use "output" key to specify function output and "error" key to specify
error details (if any). If "output" and "error" keys are not specified,
then whole "response" is treated as function output.
</pre>

<code>.google.protobuf.Struct response = 2 [(.google.api.field_behavior) = REQUIRED];</code>
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/FunctionResponse.java