public scannerOpenWithPrefix_args setStartAndPrefix(@org.apache.thrift.annotation.Nullable java.nio.ByteBuffer startAndPrefix) {
      this.startAndPrefix = org.apache.thrift.TBaseHelper.copyBinary(startAndPrefix);
      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