我正在使用jdbc接收器连接器尝试kafka和postgres接收器。
例外情况：

INFO Unable to connect to database on attempt 1/3. Will retry in 10000 ms. (io.confluent.connect.jdbc.util.CachedConnectionProvider:91)
java.sql.SQLException: No suitable driver found for jdbc:postgresql://localhost:5432/casb
at java.sql.DriverManager.getConnection(DriverManager.java:689)
    at java.sql.DriverManager.getConnection(DriverManager.java:247)
    at io.confluent.connect.jdbc.util.CachedConnectionProvider.newConnection(CachedConnectionProvider.java:85)
    at io.confluent.connect.jdbc.util.CachedConnectionProvider.getValidConnection(CachedConnectionProvider.java:68)
    at io.confluent.connect.jdbc.sink.JdbcDbWriter.write(JdbcDbWriter.java:56)
    at io.confluent.connect.jdbc.sink.JdbcSinkTask.put(JdbcSinkTask.java:69)
    at org.apache.kafka.connect.runtime.WorkerSinkTask.deliverMessages(WorkerSinkTask.java:495)
    at org.apache.kafka.connect.runtime.WorkerSinkTask.poll(WorkerSinkTask.java:288)
    at org.apache.kafka.connect.runtime.WorkerSinkTask.iteration(WorkerSinkTask.java:198)
    at org.apache.kafka.connect.runtime.WorkerSinkTask.execute(WorkerSinkTask.java:166)
    at org.apache.kafka.connect.runtime.WorkerTask.doRun(WorkerTask.java:170)
    at org.apache.kafka.connect.runtime.WorkerTask.run(WorkerTask.java:214)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
    at java.lang.Thread.run(Thread.java:748)

sink.properties属性：

name=test-sink
connector.class=io.confluent.connect.jdbc.JdbcSinkConnector
tasks.max=1
topics=fp_test
connection.url=jdbc:postgresql://localhost:5432/casb
connection.user=admin
connection.password=***
auto.create=true

我已经准备好了 plugin.path=/usr/share/java/kafka-connect-jdbc 在/usr/share/java/kafka connect jdbc上，我有以下文件： kafka-connect-jdbc-4.0.0.jar , postgresql-9.4-1206-jdbc41.jar , sqlite-jdbc-3.8.11.2.jar 其他一些jar基本上是和合流一起 Package 的。
然后我下载了postgresjdbc驱动程序jar postgresql-42.2.2.jar ，将其复制到同一文件夹中，然后重试。还是一样的例外。
请帮我解决这个问题。