vertica spark connector issue

I'm trying to write spark DataSet to vertica with the latest spark connector. But can't create the BaseRelation with below error.

Exception in thread "streaming-job-executor-1" java.lang.AbstractMethodError: com.vertica.spark.datasource.DefaultSource.createRelation(Lorg/apache/spark/sql/SQLContext;Lorg/apache/spark/sql/SaveMode;Lscala/collection/immutable/Map;Lorg/apache/spark/sql/Dataset;)Lorg/apache/spark/sql/sources/BaseRelation;
at org.apache.spark.sql.execution.datasources.DataSource.write(DataSource.scala:442)
at org.apache.spark.sql.DataFrameWriter.save(DataFrameWriter.scala:211)

This is the connection code I used:

Dataset<Row> employeeDataFrame = spark.createDataFrame(employeeRecordJavaRDD, Employee.class);
employeeDataFrame.schema();
employeeDataFrame.show();

employeeDataFrame.toDF().write()
 .format("com.vertica.spark.datasource.DefaultSource")
 .option("table", "employee")
 .option("db", "hc")
 .option("user", "dbadmin")
 .option("password", "xx")
 .option("host", "10.3.x.1x")
 .option("hdfs_url", "hdfs://hadoop:9000/user/hadoop/hc")
 .option("web_hdfs_url", "webhdfs://hadoop:50070/user/hadoop/hc")
 .option("dbschema", "hce")
 .option("port", "5433")
 .mode(SaveMode.Append).save();

I also tried

employeeDataFrame.write()

 Got the same error.

Could anyone help to point out what I did wrong? Thanks.