fix(cassandra): omit empty keyspace in jdbc url

agents/drivers/cassandra/src/main/java/com/dbx/agent/cassandra/CassandraAgent.java

@@ -159,8 +159,11 @@ public final class CassandraAgent extends AbstractJdbcAgent {
         });
     }
 
-    private static String buildUrl(ConnectParams params) {
+    static String buildUrl(ConnectParams params) {
-        return "jdbc:cassandra://" + params.getHost() + ":" + params.getPort() + "/" + params.getDatabase();
+        String baseUrl = "jdbc:cassandra://" + params.getHost() + ":" + params.getPort();
+        String keyspace = coalesce(params.getDatabase()).trim();
+        // Cassandra rejects an empty keyspace path; omit it so DBX can connect first and list keyspaces.
+        return keyspace.isEmpty() ? baseUrl : baseUrl + "/" + keyspace;
     }
 
     private static List<String> targetColumns(String options) {

agents/drivers/cassandra/src/test/java/com/dbx/agent/cassandra/CassandraAgentTest.java

@@ -1,7 +1,11 @@
 package com.dbx.agent.cassandra;
 
+import com.dbx.agent.ConnectParams;
 import com.dbx.agent.DatabaseAgent;
 import com.dbx.agent.test.JdbcFakeExecutionBehaviorTest;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 class CassandraAgentTest extends JdbcFakeExecutionBehaviorTest {
     @Override
@@ -13,4 +17,18 @@ class CassandraAgentTest extends JdbcFakeExecutionBehaviorTest {
     protected String resultSetSql() {
         return "LIST ROLES";
     }
+
+    @Test
+    void buildsServerUrlWhenKeyspaceIsEmpty() {
+        ConnectParams params = new ConnectParams("127.0.0.1", 9042, "", "cassandra", "cassandra", "", "", false);
+
+        assertEquals("jdbc:cassandra://127.0.0.1:9042", CassandraAgent.buildUrl(params));
+    }
+
+    @Test
+    void buildsKeyspaceUrlWhenKeyspaceIsSet() {
+        ConnectParams params = new ConnectParams("127.0.0.1", 9042, "app_keyspace", "cassandra", "cassandra", "", "", false);
+
+        assertEquals("jdbc:cassandra://127.0.0.1:9042/app_keyspace", CassandraAgent.buildUrl(params));
+    }
 }