title: VectorUDT usage
body: <p>I have to get the datatype and do a case match and convert it to some required format. But the usage of <code>org.apache.spark.ml.linalg.VectorUDT</code> is showing <code>VectorUDT</code> is <code>private</code>. Also I specifically need to use <code>org.apache.spark.ml.linalg.VectorUDT</code> and not <code>org.apache.spark.mllib.linalg.VectorUDT</code>. Can someone suggest how to go about this?</p>