我正在运行flume从twitter中提取数据。在执行这个命令时，我得到了这个错误。我不明白出了什么问题。
18/03/25 16:04:46错误lifecycle.Lifecycles主管：无法启动eventdrivensourcerunner:{source:com.cloudera.flume.source.twittersource{name:twitter,state:idle}}-异常如下。java.lang.nullpointerexception异常
我得到下面的日志。

18/03/25 16:04:46 INFO node.AbstractConfigurationProvider: Channel MemCh connected to [Twitter, HDFS]
18/03/25 16:04:46 INFO node.Application: Starting new configuration:{ sourceRunners:{Twitter=EventDrivenSourceRunner: { source:com.cloudera.flume.source.TwitterSource{name:Twitter,state:IDLE} }} sinkRunners:{HDFS=SinkRunner: { policy:org.apache.flume.sink.DefaultSinkProcessor@6f044771 counterGroup:{ name:null counters:{} } }} channels:{MemCh=org.apache.flume.channel.MemoryChannel{name: MemCh}} }
18/03/25 16:04:46 INFO node.Application: Starting Channel MemCh
18/03/25 16:04:46 INFO instrumentation.MonitoredCounterGroup: Monitored counter group for type: CHANNEL, name: MemCh: Successfully registered new MBean.
18/03/25 16:04:46 INFO instrumentation.MonitoredCounterGroup: Component type: CHANNEL, name: MemCh started
18/03/25 16:04:46 INFO node.Application: Starting Sink HDFS
18/03/25 16:04:46 INFO node.Application: Starting Source Twitter
18/03/25 16:04:46 INFO instrumentation.MonitoredCounterGroup: Monitored counter group for type: SINK, name: HDFS: Successfully registered new MBean.
18/03/25 16:04:46 INFO instrumentation.MonitoredCounterGroup: Component type: SINK, name: HDFS started
18/03/25 16:04:46 ERROR lifecycle.LifecycleSupervisor: Unable to start EventDrivenSourceRunner: { source:com.cloudera.flume.source.TwitterSource{name:Twitter,state:IDLE} } - Exception follows.
java.lang.NullPointerException
    at com.cloudera.flume.source.TwitterSource.start(TwitterSource.java:171)
    at org.apache.flume.source.EventDrivenSourceRunner.start(EventDrivenSourceRunner.java:44)
    at org.apache.flume.lifecycle.LifecycleSupervisor$MonitorRunnable.run(LifecycleSupervisor.java:249)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)
18/03/25 16:04:49 ERROR lifecycle.LifecycleSupervisor: Unable to start EventDrivenSourceRunner: { source:com.cloudera.flume.source.TwitterSource{name:Twitter,state:IDLE} } - Exception follows.
java.lang.NullPointerException
    at com.cloudera.flume.source.TwitterSource.start(TwitterSource.java:171)
    at org.apache.flume.source.EventDrivenSourceRunner.start(EventDrivenSourceRunner.java:44)
    at org.apache.flume.lifecycle.LifecycleSupervisor$MonitorRunnable.run(LifecycleSupervisor.java:249)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180)
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)
^C18/03/25 16:04:51 INFO lifecycle.LifecycleSupervisor: Stopping lifecycle supervisor 12
18/03/25 16:04:51 INFO node.PollingPropertiesFileConfigurationProvider: Configuration provider stopping
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Component type: SINK, name: HDFS stopped
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Shutdown Metric for type: SINK, name: HDFS. sink.start.time == 1521993886561
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Shutdown Metric for type: SINK, name: HDFS. sink.stop.time == 1521993891665
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Shutdown Metric for type: SINK, name: HDFS. sink.batch.complete == 0
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Shutdown Metric for type: SINK, name: HDFS. sink.batch.empty == 2
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Shutdown Metric for type: SINK, name: HDFS. sink.batch.underflow == 0
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Shutdown Metric for type: SINK, name: HDFS. sink.connection.closed.count == 0
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Shutdown Metric for type: SINK, name: HDFS. sink.connection.creation.count == 0
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Shutdown Metric for type: SINK, name: HDFS. sink.connection.failed.count == 0
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Shutdown Metric for type: SINK, name: HDFS. sink.event.drain.attempt == 0
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Shutdown Metric for type: SINK, name: HDFS. sink.event.drain.sucess == 0
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Component type: CHANNEL, name: MemCh stopped
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Shutdown Metric for type: CHANNEL, name: MemCh. channel.start.time == 1521993886559
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Shutdown Metric for type: CHANNEL, name: MemCh. channel.stop.time == 1521993891666
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Shutdown Metric for type: CHANNEL, name: MemCh. channel.capacity == 10000
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Shutdown Metric for type: CHANNEL, name: MemCh. channel.current.size == 0
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Shutdown Metric for type: CHANNEL, name: MemCh. channel.event.put.attempt == 0
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Shutdown Metric for type: CHANNEL, name: MemCh. channel.event.put.success == 0
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Shutdown Metric for type: CHANNEL, name: MemCh. channel.event.take.attempt == 2
18/03/25 16:04:51 INFO instrumentation.MonitoredCounterGroup: Shutdown Metric for type: CHANNEL, name: MemCh. channel.event.take.success == 0

Flume配置如下：

TwitterAgent.sources = Twitter
    TwitterAgent.channels = MemCh
    TwitterAgent.sinks = HDFS

    TwitterAgent.sources.Twitter.type = com.cloudera.flume.source.TwitterSource
    TwitterAgent.sources.Twitter.channels = MemCh
    TwitterAgent.sources.Twitter.consumerKey=
    TwitterAgent.sources.Twitter.consumerSecret=
    TwitterAgent.sources.Twitter.accessToken=
    TwitterAgent.sources.Twitter.accessTokenSecret=

    TwitterAgent.sources.Twitter.keywords = google,microsoft,apple,facebook,tesla,oracle,infosys,tcs
    TwitterAgent.sources.Twitter.language = en

    TwitterAgent.sinks.HDFS.channel = MemCh
    TwitterAgent.sinks.HDFS.type = hdfs
    TwitterAgent.sinks.HDFS.hdfs.path = hdfs://localhost:9000/flume/Twitter/PublicStream/day_key=%Y%m%d/
    TwitterAgent.sinks.HDFS.hdfs.fileType = DataStream
    TwitterAgent.sinks.HDFS.hdfs.writeformat=Text
    TwitterAgent.sinks.HDFS.hdfs.batchSize=1000
    TwitterAgent.sinks.HDFS.hdfs.rollSize=0
    TwitterAgent.sinks.HDFS.hdfs.rollCount=10000
    TwitterAgent.sinks.HDFS.hdfs.rollInterval=600

    TwitterAgent.channels.MemCh.type = memory
    TwitterAgent.channels.MemCh.capacity = 10000
    TwitterAgent.channels.MemCh.transactionCapacity = 1000