code: public void beforeConvert(SO outputSchema, DI inputRecord, WorkUnitState workUnit) {
      Instrumented.markMeter(this.recordsInMeter);
    }
docs: Called before conversion.
  @param outputSchema output schema of the {@link #convertSchema(Object, WorkUnitState)} method
  @param inputRecord an input data record
  @param workUnit a {@link WorkUnitState} instance