我想为以前被覆盖的主题删除配置（将其重置为默认值）。这可以通过提供的脚本实现

$> ./kafka-configs.sh --zookeeper localhost:2181 --alter --entity-type topics \
--entity-name test --delete-config my.overridden.config

有没有办法使用kafka-clients-1.1.1.jar中提供的kafkaadminclient来实现这一点？
我刚找到方法 org.apache.kafka.clients.admin.KafkaAdminClient.alterConfigs(Map<ConfigResource, Config>, AlterConfigsOptions) ，但当我使用设置为null的配置值调用它时，服务器上会出现一个nullpointerexception：

[2018-07-31 11:24:01,658] ERROR [Admin Manager on Broker 0]: Error processing alter configs request for resource Resource(type=TOPIC, name='test'}, config org.apache.kafka.common.requests.AlterConfigsRequest$Config@5d4fef59 (kafka.server.AdminManager)
java.lang.NullPointerException
    at java.util.Hashtable.put(Hashtable.java:459)
    at java.util.Properties.setProperty(Properties.java:166)
    at kafka.server.AdminManager$$anonfun$alterConfigs$1$$anonfun$apply$18.apply(AdminManager.scala:357)
    at kafka.server.AdminManager$$anonfun$alterConfigs$1$$anonfun$apply$18.apply(AdminManager.scala:356)
    at scala.collection.Iterator$class.foreach(Iterator.scala:891)
    at scala.collection.AbstractIterator.foreach(Iterator.scala:1334)
    at scala.collection.IterableLike$class.foreach(IterableLike.scala:72)
    at scala.collection.AbstractIterable.foreach(Iterable.scala:54)
    at kafka.server.AdminManager$$anonfun$alterConfigs$1.apply(AdminManager.scala:356)
    at kafka.server.AdminManager$$anonfun$alterConfigs$1.apply(AdminManager.scala:339)
    at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
    at scala.collection.TraversableLike$$anonfun$map$1.apply(TraversableLike.scala:234)
    at scala.collection.Iterator$class.foreach(Iterator.scala:891)
    at scala.collection.AbstractIterator.foreach(Iterator.scala:1334)
    at scala.collection.IterableLike$class.foreach(IterableLike.scala:72)
    at scala.collection.AbstractIterable.foreach(Iterable.scala:54)
    at scala.collection.TraversableLike$class.map(TraversableLike.scala:234)
    at scala.collection.AbstractTraversable.map(Traversable.scala:104)
    at kafka.server.AdminManager.alterConfigs(AdminManager.scala:339)
    at kafka.server.KafkaApis.handleAlterConfigsRequest(KafkaApis.scala:1987)
    at kafka.server.KafkaApis.handle(KafkaApis.scala:136)
    at kafka.server.KafkaRequestHandler.run(KafkaRequestHandler.scala:69)
    at java.lang.Thread.run(Thread.java:745)

空列表也不起作用。
我在2.11-1.1.0版本中使用Kafka。