Pass empty Configuration in DelegatingCluster

[ebyhr]

Otherwise, it causes NPE at https://github.com/yugabyte/cassandra-java-driver/blob/3.8.0-yb-x/driver-core/src/main/java/com/datastax/driver/core/Cluster.java#L1620

[ebyhr]

@tedyu @nmalladi Could you review this PR when you have time?

[ebyhr]

@tedyu @nmalladi Gentle reminder.

[tedyu]

Seems reasonable to me.

@nchandrappa
What do you think ?

[nchandrappa]

Hello @ebyhr, Thanks for submitting the PR.

You have mentioned the code fix is to prevent an NPE, is it possible to define a test case scenario when NPE can occur.

Also, DelegatingCluster is an abstract class, and based on the DelegatingClusterIntegrationTest super constructor is not getting invoked. can you please provide the requested details before merging the PR?

Thanks,
Nikhil

[ebyhr]

Here is the test case that fails before this change and succeeds after that.

import static org.testng.Assert.assertNotNull;

import org.testng.annotations.Test;

public class DelegateClusterTest {
  @Test(groups = "short")
  public void should_not_throw_null_pointer_exception() {
    Cluster cluster = Cluster.builder().addContactPoints("localhost").build();
    SimpleDelegatingCluster delegatingCluster = new SimpleDelegatingCluster(cluster);
    assertNotNull(delegatingCluster);
  }

  private static class SimpleDelegatingCluster extends DelegatingCluster {
    private final Cluster cluster;

    SimpleDelegatingCluster(Cluster cluster) {
      this.cluster = cluster;
    }

    @Override
    protected Cluster delegate() {
      return cluster;
    }
  }
}

[nchandrappa]

Thanks for providing the testcase @ebyhr. Code fix looks good.

[nchandrappa]

LGTM.