@Override
  public Long increment(Long o) {
    return o == null ? null : (o + 1l);
  }
a concrete column interpreter implementation. The cell value is a Long value and its promoted
data type is also a Long value. For computing aggregation function, this class is used to find
the datatype of the cell value. Client is supposed to instantiate it and passed along as a
parameter. See TestAggregateProtocol methods for its sample usage. Its methods handle null
arguments gracefully.
hbase-client/src/main/java/org/apache/hadoop/hbase/client/coprocessor/LongColumnInterpreter.java