public com.google.protobuf.ByteString getPostProcessingCloudFunctionBytes() {
      java.lang.Object ref = postProcessingCloudFunction_;
      if (ref instanceof String) {
        com.google.protobuf.ByteString b =
            com.google.protobuf.ByteString.copyFromUtf8((java.lang.String) ref);
        postProcessingCloudFunction_ = b;
        return b;
      } else {
        return (com.google.protobuf.ByteString) ref;
      }
    }
<pre>
If not empty, the prediction result will be sent to the specified cloud
function for post processing.
* The cloud function will receive AppPlatformCloudFunctionRequest where
the annotations field will be the json format of proto PredictResponse.
* The cloud function should return AppPlatformCloudFunctionResponse with
PredictResponse stored in the annotations field.
* To drop the prediction output, simply clear the payload field in the
returned AppPlatformCloudFunctionResponse.
</pre>

<code>string post_processing_cloud_function = 3;</code>

@return The bytes for postProcessingCloudFunction.
java-visionai/proto-google-cloud-visionai-v1/src/main/java/com/google/cloud/visionai/v1/VertexCustomConfig.java