public com.google.cloud.videointelligence.v1p2beta1.LabelAnnotation.Builder
        addFrameLabelAnnotationsBuilder(int index) {
      return getFrameLabelAnnotationsFieldBuilder()
          .addBuilder(
              index,
              com.google.cloud.videointelligence.v1p2beta1.LabelAnnotation.getDefaultInstance());
    }
<pre>
Label annotations on frame level.
There is exactly one element for each unique label.
</pre>

<code>
repeated .google.cloud.videointelligence.v1p2beta1.LabelAnnotation frame_label_annotations = 4;
</code>
java-video-intelligence/proto-google-cloud-video-intelligence-v1p2beta1/src/main/java/com/google/cloud/videointelligence/v1p2beta1/VideoAnnotationResults.java