OutputStream getOutputStream() {
    FSDataOutputStream fsdos = this.hdfs_out;
    return fsdos != null ? fsdos.getWrappedStream() : null;
  }
Currently, we need to expose the writer's OutputStream to tests so that they can manipulate the
default behavior (such as setting the maxRecoveryErrorCount value). This is done using
reflection on the underlying HDFS OutputStream. NOTE: This could be removed once Hadoop1
support is removed.
@return null if underlying stream is not ready.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/FSHLog.java