public void writeBloom(ExtendedCell cell) throws IOException {
    // only add to the bloom filter on a new, unique key
    if (isNewKey(cell)) {
      sanityCheck(cell);
      bloomFilterWriter.append(cell);
    }
  }
Bloom information from the cell is retrieved
hbase-server/src/main/java/org/apache/hadoop/hbase/util/BloomContext.java