Can not run examples under Spark 2.4

[GangLiCN]

Spark-Bench version (version number, tag, or git commit hash)

2.3.0

Livy Server version

0.5

Details of your cluster setup (Spark version, Standalone/Yarn/Local/Etc)

Spark version: 2.4.0 (installed from "spark-2.4.0-bin-hadoop2.7.tgz")
type: Single node, no hadoop, just installed Livy server

Scala version on your cluster

2.11.12

Your exact configuration file (with system details anonymized for security)

The content of "local-livy-example.conf":

spark-bench = {
spark-submit-config = [{
livy = {
url = "<my_spark_server_ip>:8998"
poll-seconds = 1
}
spark-bench-jar = "/root/packages/apache/spark/spark-bench_2.3.0_0.4.0-RELEASE/lib/spark-bench-2.3.0_0.4.0-RELEASE.jar"
workload-suites = [
{
descr = "One run of SparkPi and that's it!"
benchmark-output = "console"
workloads = [
{
name = "sparkpi"
slices = 10
}
]
}
]
}]
}

Relevant stacktrace

Exception in thread "main" com.ibm.sparktc.sparkbench.utils.SparkBenchException: REST call returned non-sucess code: 400
at com.ibm.sparktc.sparkbench.sparklaunch.submission.livy.LivySubmit$$anonfun$2.apply(LivySubmit.scala:37)
at com.ibm.sparktc.sparkbench.sparklaunch.submission.livy.LivySubmit$$anonfun$2.apply(LivySubmit.scala:37)
at com.ibm.sparktc.sparkbench.sparklaunch.submission.livy.LivySubmit$.sendPostBatchRequest(LivySubmit.scala:61)
at com.ibm.sparktc.sparkbench.sparklaunch.submission.livy.LivySubmit.launch(LivySubmit.scala:102)
at com.ibm.sparktc.sparkbench.sparklaunch.SparkLaunch$.com$ibm$sparktc$sparkbench$sparklaunch$SparkLaunch$$launch$1(SparkLaunch.scala:57)
at com.ibm.sparktc.sparkbench.sparklaunch.SparkLaunch$$anonfun$launchJobs$2.apply(SparkLaunch.scala:65)
at com.ibm.sparktc.sparkbench.sparklaunch.SparkLaunch$$anonfun$launchJobs$2.apply(SparkLaunch.scala:65)
at scala.collection.immutable.List.foreach(List.scala:381)
at com.ibm.sparktc.sparkbench.sparklaunch.SparkLaunch$.launchJobs(SparkLaunch.scala:65)
at com.ibm.sparktc.sparkbench.sparklaunch.SparkLaunch$.main(SparkLaunch.scala:38)
at com.ibm.sparktc.sparkbench.sparklaunch.SparkLaunch.main(SparkLaunch.scala)
Caused by: java.lang.Exception
at com.ibm.sparktc.sparkbench.utils.SparkBenchException$.apply$default$2(SparkBenchException.scala:22)
... 11 more

Description of your problem and any other relevant info

I can't run example(e.g. local-livy-example.conf) using "spark-bench", detailed error stack is as above.
Not sure if it's a compatibility issue between livy server and speark-bench.