@Override
    public String toString() {
        StringBuilder bld = new StringBuilder();
        bld.append("Assignment");
        bld.append("(topicIdPartition=").append(topicIdPartition);
        bld.append(", directoryId=").append(directoryId);
        bld.append(", submissionTimeNs=").append(submissionTimeNs);
        bld.append(", successCallback=").append(successCallback);
        bld.append(")");
        return bld.toString();
    }
@Test
    public void testAssignmentToString() {
        assertEquals("Assignment(topicIdPartition=rTudty6ITOCcO_ldVyzZYg:1, " +
            "directoryId=rzRT8XZaSbKsP6j238zogg, " +
            "submissionTimeNs=123, " +
            "successCallback=NoOpRunnable)",
            new Assignment(new TopicIdPartition(Uuid.fromString("rTudty6ITOCcO_ldVyzZYg"), 1),
                Uuid.fromString("rzRT8XZaSbKsP6j238zogg"),
                123,
                NoOpRunnable.INSTANCE).toString());
    }