code: private void verifyFirstBlock() {
      BlockScanInfo block = null;
      synchronized (this) {
        if ( blockInfoSet.size() > 0 ) {
          block = blockInfoSet.first();
        }
      }
      
      if ( block != null ) {
        verifyBlock(block);
        processedBlocks.add(block.block.getBlockId());
      }
    }
docs: Picks one block and verifies it