@Override
        public void close() throws IOException {
          trr.close();
          connection.close();
        }
Builds a TableRecordReader. If no TableRecordReader was provided, uses the default.
@param split   The split to work with.
@param context The current context.
@return The newly created record reader.
@throws IOException          When creating the reader fails.
@throws InterruptedException when record reader initialization fails
@see InputFormat#createRecordReader(InputSplit, TaskAttemptContext)
hbase-mapreduce/src/main/java/org/apache/hadoop/hbase/mapreduce/MultiTableInputFormatBase.java