public void allocBloom() {
    if (this.bloom != null) {
      throw new IllegalArgumentException("can only create bloom once.");
    }
    this.bloom = ByteBuffer.allocate((int) this.byteSize);
    assert this.bloom.hasArray();
  }
Creates another similar Bloom filter. Does not copy the actual bits, and sets the new filter's
key count to zero.
@return a Bloom filter with the same configuration as this
hbase-server/src/main/java/org/apache/hadoop/hbase/util/BloomFilterChunk.java