code: private RelationType getRelationType(Integer gpType)
     {
        RelationType result = null;
        if (gpType != null)
        {
           int index = NumberHelper.getInt(gpType);
           if (index > 0 && index < RELATION.length)
           {
              result = RELATION[index];
           }
        }
  
        if (result == null)
        {
           result = RelationType.FINISH_START;
        }
  
        return result;
     }
docs: Convert a GanttProject task relationship type into an MPXJ RelationType instance.
  
  @param gpType GanttProject task relation type
  @return RelationType instance