title: Convert timestamp column from UTC to EST in spark scala
body: <p>I have a column in spark dataframe of timestamp type with date format like '2019-06-13T11:39:10.244Z'
  My goal is to convert this column into EST time(subtracting 4 hours) keeping the same format.
  I tried it using from_utc_timestamp api but it seems it is converting the UTC time to my local timezone (+5:30) and adding it to the timestamp then subtracting 4 hours from it. I tried to use Joda time but for some reason it is adding 33 days to the EST time</p>
  
  <p>innput = 2019-06-13T11:39:10.244Z</p>
  
  <p>using from_utc_timestamp api:</p>
  
  <pre><code>val tDf = df.withColumn("newTimeCol", to_utc_timestamp(col("timeCol"), "America/New_York"))
  </code></pre>
  
  <p>output = 2019-06-13T13:09:10.244Z+5:30</p>
  
  <p>using Joda time package:</p>
  
  <pre><code>   val coder : (String =&gt; String) = (arg: String) =&gt; {
       new DateTime(arg, DateTimeZone.UTC).minusHours(4).toString("yyyy-mm-dd'T'HH:mm:s.SS'Z'")}
     val sqlfunc = udf(coder)
     val tDf = df.withColumn("newTime", sqlfunc(col("_c20")))
  </code></pre>
  
  <p>output = 2019-39-13T07:39:10.244Z</p>
  
  <p>desired output = 2019-06-13T07:39:10.244Z</p>
  
  <p>Kindly advise how should I proceed. Thanks in advance</p>