title: How to join with lowercase column values in a spark DF
body: <pre><code> val df_final = Data1
          .join(broadcast(df),
            Seq(lower(col("NAME")),  lower(col("TYPE"))),
            "left")
  </code></pre>
  
  <p>The above code is throwing the below error.</p>
  
  <pre><code>&lt;console&gt;:65: error: overloaded method value join with alternatives:
    (right: org.apache.spark.sql.Dataset[_],joinExprs: org.apache.spark.sql.Column,joinType: String)org.apache.spark.sql.DataFrame &lt;and&gt;
    (right: org.apache.spark.sql.Dataset[_],usingColumns: Seq[String],joinType: String)org.apache.spark.sql.DataFrame
   cannot be applied to (org.apache.spark.sql.Dataset[org.apache.spark.sql.Row], Seq[org.apache.spark.sql.Column], String)
                 .join(broadcast(df),
              ^
  </code></pre>