code: public Datapoint addLongValue(long time, long value) {
          initialValues();
          checkType(TsdbConstants.TYPE_LONG);
  
          values.add(Lists.<JsonNode> newArrayList(new LongNode(time), new LongNode(value)));
          return this;
      }
docs: Add datapoint of long type value.
  
  @param time datapoint's timestamp
  @param value datapoint's value
  @return Datapoint