title: java.lang.UnsupportedOperationException: Data source org.apache.spark.sql.redis does not support streamed reading
body: <p>Trying to read data from Redis with spark 2.3(java) code.
  Able to read the non-streaming data from Redis, <strong>but unable to read data in case of streamed reading from Redis</strong>, I get the following errors:
  1) when I specify the format as :</p>
  
  <pre><code>Dataset&lt;Row&gt; RedisData = spark.readStream()
                            .format("org.apache.spark.sql.redis")
                            .option("stream.keys","carsstream")
                            .schema(UserSchema5)
                            .load();
  </code></pre>
  
  <p>The error is :</p>
  
  <pre><code>java.lang.UnsupportedOperationException: Data source org.apache.spark.sql.redis does not support streamed reading
  </code></pre>
  
  <p>2) when I specify the format as :</p>
  
  <pre><code>Dataset&lt;Row&gt; RedisData = spark.readStream()
                                .format("redis")
                                .option("stream.keys","carsstream")
                                .schema(UserSchema5)
                                .load();
  </code></pre>
  
  <p>The error is</p>
  
  <pre><code>java.lang.ClassNotFoundException: Failed to find data source: redis. Please find packages at http://spark.apache.org/third-party-projects.html
  </code></pre>
  
  <p>I have specified jars of <code>Jedis(version 3.1.0)</code>, <code>spark-redis(2.3.1)</code>, <code>spark-core_2.11(version 2.3.0)</code>.    </p>
  
  <p>Any suggestions would be helpful.</p>