Constuctor public ClientInfoException(Properties failedProperties, Throwable cause) does not properly initialize the Reason if cause is not null. The spec says:
...
The reason is initialized to null if cause==null or to cause.toString() if cause!=null and the vendor code is initialized to 0.
...

In fact, the getMessage() returns null reason even the cause is not null. See example below:

import java.sql.ClientInfoException;
import java.util.Properties;

/
public class Test {
    
    /** Creates a new instance of Test */

    
    public static void main(String[] argv) {
        final Throwable cause = new Throwable();
        final ClientInfoException e = new ClientInfoException(new Properties(),
                        cause);
        System.out.println("Returned: " + e.getMessage());
        // The reason is initialized to null if cause==null or to
        //cause.toString() if cause!=null and the vendor code is
        //initialized to 0.
        System.out.println("Expected: " + cause.toString());
    }
}

run-single:
Returned: null
Expected: java.lang.Throwable