private com.google.protobuf.SingleFieldBuilderV3<
            com.google.cloud.vision.v1p2beta1.ImageAnnotationContext,
            com.google.cloud.vision.v1p2beta1.ImageAnnotationContext.Builder,
            com.google.cloud.vision.v1p2beta1.ImageAnnotationContextOrBuilder>
        getContextFieldBuilder() {
      if (contextBuilder_ == null) {
        contextBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.cloud.vision.v1p2beta1.ImageAnnotationContext,
                com.google.cloud.vision.v1p2beta1.ImageAnnotationContext.Builder,
                com.google.cloud.vision.v1p2beta1.ImageAnnotationContextOrBuilder>(
                getContext(), getParentForChildren(), isClean());
        context_ = null;
      }
      return contextBuilder_;
    }
<pre>
If present, contextual information is needed to understand where this image
comes from.
</pre>

<code>.google.cloud.vision.v1p2beta1.ImageAnnotationContext context = 21;</code>
java-vision/proto-google-cloud-vision-v1p2beta1/src/main/java/com/google/cloud/vision/v1p2beta1/AnnotateImageResponse.java