long reportInterval() {
            return options.valueOf(reportIntervalOpt);
        }
For verifying the consistency among replicas.
<p>
 1. start a fetcher on every broker
 2. each fetcher does the following
   2.1 issues fetch request
   2.2 puts the fetched result in a shared buffer
   2.3 waits for all other fetchers to finish step 2.2
   2.4 one of the fetchers verifies the consistency of fetched results among replicas
<p>
The consistency verification is up to the high watermark. The tool reports the
max lag between the verified offset and the high watermark among all partitions.
<p>
If a broker goes down, the verification of the partitions on that broker is delayed
until the broker is up again.
<p>
Caveats:
1. The tool needs all brokers to be up at startup time.
2. The tool doesn't handle out of range offsets.
tools/src/main/java/org/apache/kafka/tools/ReplicaVerificationTool.java