@java.lang.Override
  public float getRollAngle() {
    return rollAngle_;
  }
<pre>
Roll angle, which indicates the amount of clockwise/anti-clockwise rotation
of the face relative to the image vertical about the axis perpendicular to
the face. Range [-180,180].
</pre>

<code>float roll_angle = 4;</code>

@return The rollAngle.
java-vision/proto-google-cloud-vision-v1p2beta1/src/main/java/com/google/cloud/vision/v1p2beta1/FaceAnnotation.java