private com.google.protobuf.SingleFieldBuilderV3<
            com.google.cloud.visionai.v1.NormalizedPolyline,
            com.google.cloud.visionai.v1.NormalizedPolyline.Builder,
            com.google.cloud.visionai.v1.NormalizedPolylineOrBuilder>
        getCrossingLineFieldBuilder() {
      if (crossingLineBuilder_ == null) {
        if (!(annotationPayloadCase_ == 6)) {
          annotationPayload_ = com.google.cloud.visionai.v1.NormalizedPolyline.getDefaultInstance();
        }
        crossingLineBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.cloud.visionai.v1.NormalizedPolyline,
                com.google.cloud.visionai.v1.NormalizedPolyline.Builder,
                com.google.cloud.visionai.v1.NormalizedPolylineOrBuilder>(
                (com.google.cloud.visionai.v1.NormalizedPolyline) annotationPayload_,
                getParentForChildren(),
                isClean());
        annotationPayload_ = null;
      }
      annotationPayloadCase_ = 6;
      onChanged();
      return crossingLineBuilder_;
    }
<pre>
Annotation for type CROSSING_LINE
</pre>

<code>.google.cloud.visionai.v1.NormalizedPolyline crossing_line = 6;</code>
java-visionai/proto-google-cloud-visionai-v1/src/main/java/com/google/cloud/visionai/v1/StreamAnnotation.java