@Override public String toString() {
    return "KafkaSupervisorIOConfig{"
        + "topic='"
        + topic
        + '\''
        + ", replicas="
        + replicas
        + ", taskCount="
        + taskCount
        + ", taskDuration="
        + taskDuration
        + ", consumerProperties="
        + consumerProperties
        + ", startDelay="
        + startDelay
        + ", period="
        + period
        + ", useEarliestOffset="
        + useEarliestOffset
        + ", completionTimeout="
        + completionTimeout
        + ", lateMessageRejectionPeriod="
        + lateMessageRejectionPeriod
        + ", skipOffsetGaps="
        + skipOffsetGaps
        + '}';
  }
This class is copied from druid source code
in order to avoid adding additional dependencies on druid-indexing-service.
druid-handler/src/java/org/apache/hadoop/hive/druid/json/KafkaSupervisorIOConfig.java