public scannerOpenWithPrefix_args setStartAndPrefix(byte[] startAndPrefix) {
      this.startAndPrefix = startAndPrefix == null ? (java.nio.ByteBuffer)null     : java.nio.ByteBuffer.wrap(startAndPrefix.clone());
      return this;
    }
the prefix (and thus start row) of the keys you want
hbase-thrift/src/main/java/org/apache/hadoop/hbase/thrift/generated/Hbase.java