private void writeInlineBlocks(boolean closing) throws IOException {
    for (InlineBlockWriter ibw : inlineBlockWriters) {
      while (ibw.shouldWriteBlock(closing)) {
        long offset = outputStream.getPos();
        boolean cacheThisBlock = ibw.getCacheOnWrite();
        ibw.writeInlineBlock(blockWriter.startWriting(ibw.getInlineBlockType()));
        blockWriter.writeHeaderAndData(outputStream);
        ibw.blockWritten(offset, blockWriter.getOnDiskSizeWithHeader(),
          blockWriter.getUncompressedSizeWithoutHeader());
        totalUncompressedBytes += blockWriter.getUncompressedSizeWithHeader();

        if (cacheThisBlock) {
          doCacheOnWrite(offset);
        }
      }
    }
  }
Gives inline block writers an opportunity to contribute blocks.
hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/HFileWriterImpl.java