@Override
    public String toString() {
        return this.value;
    }
Specify whether the encoder uses B-frames as reference frames for other pictures in the same GOP. Choose Allow to
allow the encoder to use B-frames as reference frames. Choose Don't allow to prevent the encoder from using B-frames
as reference frames.
aws-java-sdk-mediaconvert/src/main/java/com/amazonaws/services/mediaconvert/model/XavcGopBReference.java