title: scala udf complains"java.lang.ClassNotFoundException"in flink sql client
body: <p>The whole scala project for UDF is here:</p>
  <p><a href="https://github.com/appleyuchi/Flink_SQL_Client_UDF/tree/master/Scala_fixed" rel="nofollow noreferrer">Flink_SQL_Client_UDF/Scala_fixed/</a></p>
  <p>My operation to register the udf is like this:</p>
  <pre><code>①mvn scala:compile package
  ②cp table_api-1.0-SNAPSHOT.jar $FLINK_HOME/lib
  ③add the following sentence into $FLINK_HOME/conf/flink-conf.yaml
  flink.execution.jars: $FLINK_HOME/lib/table_api-1.0-SNAPSHOT.jar
  ④create temporary function scalaupper as 'ScalaUpper';
  ⑤CREATE TABLE orders (
      order_uid  BIGINT,
      product_name String,
      price      DECIMAL(32, 2),
      order_time TIMESTAMP(3)
  ) WITH (
      'connector' = 'datagen'
  );
  ⑥select scalaupper(product_name) from orders;
  </code></pre>
  <p>Then I got</p>
  <p>java.lang.ClassNotFoundException: ScalaUpper</p>
  <p><a href="https://i.stack.imgur.com/Tyaxa.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Tyaxa.png" alt="error" /></a></p>
  <p>Need your help, thanks!</p>