public void start(boolean initializationMustReadToEnd) {
        this.initializationMustReadToEnd = initializationMustReadToEnd;
        log.debug("OffsetSyncStore starting - must read to OffsetSync end = {}", initializationMustReadToEnd);
        backingStoreStart();
        readToEnd = true;
    }
Start the OffsetSyncStore, blocking until all previous Offset Syncs have been read from backing storage.
connect/mirror/src/main/java/org/apache/kafka/connect/mirror/OffsetSyncStore.java