public void map(ImmutableBytesWritable key, Result value,
    OutputCollector<ImmutableBytesWritable, Result> output, Reporter reporter) throws IOException {

    // convert
    output.collect(key, value);
  }
Pass the key, value to reduce
hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/mapred/IdentityTableMap.java