@Override
  public void checkOutputSpecs(FileSystem ignored, JobConf job)
    throws FileAlreadyExistsException, InvalidJobConfException, IOException {
    String tableName = job.get(OUTPUT_TABLE);
    if (tableName == null) {
      throw new IOException("Must specify table name");
    }
  }
Creates a new record writer. Be aware that the baseline javadoc gives the impression that there
is a single {@link RecordWriter} per job but in HBase, it is more natural if we give you a new
RecordWriter per call of this method. You must close the returned RecordWriter when done.
Failure to do so will drop writes.
@param ignored Ignored filesystem
@param job     Current JobConf
@param name    Name of the job
@return The newly created writer instance.
@throws IOException When creating the writer fails.
hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/mapred/TableOutputFormat.java