title: java.lang.NullPointerException:null at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:877) in pulsar-io-jdbc connecttor
body: <p>I am Using Apache Pulsar v2.4.2.And taken refrence of pulsar-io-jdbc and created custom sink connector packaged nar.</p>
  
  <p>And running the following commands to upload schema and create connector</p>
  
  <p>1.<strong>Uploaded AVRO Schema</strong>. </p>
  
  <pre><code>bin/pulsar-admin schemas upload myjdbc --filename ./connectors/pulsar-io-jdbc-schema.conf
  </code></pre>
  
  <p>Here is the avro schema:</p>
  
  <pre><code>{
    "type": "AVRO",
    "schema": "{\"type\":\"record\",\"name\":\"Test\",\"fields\":[{\"name\":\"id\",\"type\":[\"null\",\"int\"]},{\"name\":\"name\",\"type\":[\"null\",\"string\"]}]}",
    "properties": {}
  }
  </code></pre>
  
  <p>2.<strong>Create connector</strong></p>
  
  <pre><code>bin/pulsar-admin sinks localrun --archive ./connectors/pulsar-io-jdbc-2.4.2.nar --inputs myjdbc --name myjdbc --sink-config-file ./connectors/pulsar-io-jdbc.yaml
  </code></pre>
  
  <p>And onces I am sending message to topic "myjdbc" from producer.SendAsync(message).
  where message is</p>
  
  <pre><code>for (int i = 0; i &lt; count; i++)
  {
     JObject obj = new JObject();
     obj.Add("id", i);
     obj.Add("name", "testing topic" + i);
     var str = obj.ToString(Formatting.None);
  
     var messageId = await producer.SendAsync(Encoding.UTF8.GetBytes(str));
                  Console.WriteLine($"MessageId is: '{messageId}'");
  }
  </code></pre>
  
  <p>Pulsar localrun connector is getting the following exception:</p>
  
  <pre><code>19:48:37.437 [pulsar-client-io-1-1] INFO  org.apache.pulsar.client.impl.ClientCnx - [id: 0x557fb218, L:/127.0.0.1:39488 - R:localhost/127.0.0.1:6650] Connected through proxy to target broker at 192.168.1.97:6650
  19:48:37.445 [pulsar-client-io-1-1] INFO  org.apache.pulsar.client.impl.ConsumerImpl - [myjdbc][public/default/myjdbc] Subscribing to topic on cnx [id: 0x557fb218, L:/127.0.0.1:39488 - R:localhost/127.0.0.1:6650]
  19:48:37.503 [pulsar-client-io-1-1] INFO  org.apache.pulsar.client.impl.ConsumerImpl - [myjdbc][public/default/myjdbc] Subscribed to topic on localhost/127.0.0.1:6650 -- consumer: 0
  19:48:37.557 [pulsar-client-io-1-1] INFO  com.scurrilous.circe.checksum.Crc32cIntChecksum - SSE4.2 CRC32C provider initialized
  19:48:37.715 [pulsar-client-io-1-1] INFO  org.apache.pulsar.client.impl.ConsumerImpl - [myjdbc] [public/default/myjdbc] Closed consumer
  19:48:37.942 [main] INFO  org.apache.pulsar.functions.LocalRunner - RuntimeSpawner quit because of
  java.lang.NullPointerException: null
          at com.google.common.base.Preconditions.checkNotNull(Preconditions.java:877) ~[com.google.guava-guava-25.1-jre.jar:?]
          at com.google.common.cache.LocalCache.get(LocalCache.java:3950) ~[com.google.guava-guava-25.1-jre.jar:?]
          at com.google.common.cache.LocalCache.getOrLoad(LocalCache.java:3973) ~[com.google.guava-guava-25.1-jre.jar:?]
          at com.google.common.cache.LocalCache$LocalLoadingCache.get(LocalCache.java:4957) ~[com.google.guava-guava-25.1-jre.jar:?]
          at org.apache.pulsar.client.impl.schema.StructSchema.decode(StructSchema.java:94) ~[org.apache.pulsar-pulsar-client-original-2.4.2.jar:2.4.2]
          at org.apache.pulsar.client.impl.schema.AutoConsumeSchema.decode(AutoConsumeSchema.java:72) ~[org.apache.pulsar-pulsar-client-original-2.4.2.jar:2.4.2]
          at org.apache.pulsar.client.impl.schema.AutoConsumeSchema.decode(AutoConsumeSchema.java:36) ~[org.apache.pulsar-pulsar-client-original-2.4.2.jar:2.4.2]
          at org.apache.pulsar.client.api.Schema.decode(Schema.java:97) ~[org.apache.pulsar-pulsar-client-api-2.4.2.jar:2.4.2]
          at org.apache.pulsar.client.impl.MessageImpl.getValue(MessageImpl.java:268) ~[org.apache.pulsar-pulsar-client-original-2.4.2.jar:2.4.2]
          at org.apache.pulsar.functions.source.PulsarRecord.getValue(PulsarRecord.java:74) ~[org.apache.pulsar-pulsar-functions-instance-2.4.2.jar:2.4.2]
          at org.apache.pulsar.functions.instance.JavaInstanceRunnable.readInput(JavaInstanceRunnable.java:473) ~[org.apache.pulsar-pulsar-functions-instance-2.4.2.jar:2.4.2]
          at org.apache.pulsar.functions.instance.JavaInstanceRunnable.run(JavaInstanceRunnable.java:246) ~[org.apache.pulsar-pulsar-functions-instance-2.4.2.jar:2.4.2]
          at java.lang.Thread.run(Thread.java:748) ~[?:1.8.0_232]
  19:49:03.105 [function-timer-thread-5-1] ERROR org.apache.pulsar.functions.runtime.RuntimeSpawner - public/default/myjdbc-java.lang.NullPointerException Function Container is dead with exception.. restarting 
  </code></pre>
  
  <p><strong>And also write() method is not triggered.</strong></p>