title: Unsupported literal type class scala.runtime.BoxedUnit
body: <p>I am trying to filter a column of a dataframe read from oracle as below</p>
  
  <pre><code>import org.apache.spark.sql.functions.{col, lit, when}
  
  val df0  =  df_org.filter(col("fiscal_year").isNotNull())
  </code></pre>
  
  <p>When I do it I am getting below error:</p>
  
  <pre><code>java.lang.RuntimeException: Unsupported literal type class scala.runtime.BoxedUnit ()
  at org.apache.spark.sql.catalyst.expressions.Literal$.apply(literals.scala:77)
  at org.apache.spark.sql.catalyst.expressions.Literal$$anonfun$create$2.apply(literals.scala:163)
  at org.apache.spark.sql.catalyst.expressions.Literal$$anonfun$create$2.apply(literals.scala:163)
  at scala.util.Try.getOrElse(Try.scala:79)
  at org.apache.spark.sql.catalyst.expressions.Literal$.create(literals.scala:162)
  at org.apache.spark.sql.functions$.typedLit(functions.scala:113)
  at org.apache.spark.sql.functions$.lit(functions.scala:96)
  at org.apache.spark.sql.Column.apply(Column.scala:212)
  at com.snp.processors.BenchmarkModelValsProcessor2.process(BenchmarkModelValsProcessor2.scala:80)
  at com.snp.utils.Utils$$anonfun$getAllDefinedProcessors$1.apply(Utils.scala:30)
  at com.snp.utils.Utils$$anonfun$getAllDefinedProcessors$1.apply(Utils.scala:30)
  at com.sp.MigrationDriver$$anonfun$main$6$$anonfun$apply$2.apply(MigrationDriver.scala:140)
  at com.sp.MigrationDriver$$anonfun$main$6$$anonfun$apply$2.apply(MigrationDriver.scala:140)
  at scala.Option.map(Option.scala:146)
  at com.sp.MigrationDriver$$anonfun$main$6.apply(MigrationDriver.scala:138)
  at com.sp.MigrationDriver$$anonfun$main$6.apply(MigrationDriver.scala:135)
  at scala.collection.TraversableLike$WithFilter$$anonfun$foreach$1.apply(TraversableLike.scala:733)
  at scala.collection.Iterator$class.foreach(Iterator.scala:891)
  at scala.collection.AbstractIterator.foreach(Iterator.scala:1334)
  at scala.collection.MapLike$DefaultKeySet.foreach(MapLike.scala:174)
  at scala.collection.TraversableLike$WithFilter.foreach(TraversableLike.scala:732)
  at com.sp.MigrationDriver$.main(MigrationDriver.scala:135)
  at com.sp.MigrationDriver.main(MigrationDriver.scala)
  </code></pre>
  
  <p>Any idea what am I doing wrong here and how to fix this?</p>