public Builder clearResponseMimeType() {
      responseMimeType_ = getDefaultInstance().getResponseMimeType();
      bitField0_ = (bitField0_ & ~0x00000800);
      onChanged();
      return this;
    }
<pre>
Optional. Output response mimetype of the generated candidate text.
Supported mimetype:
- `text/plain`: (default) Text output.
- `application/json`: JSON response in the candidates.
The model needs to be prompted to output the appropriate response type,
otherwise the behavior is undefined.
This is a preview feature.
</pre>

<code>string response_mime_type = 13 [(.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