def specific_occurrence_source_data_criteria(force_sources=nil)
      return [] if @source_data_criteria.nil?
      matching = @source_data_criteria.select {|dc| !dc.specific_occurrence.nil?}

      if force_sources
        existing = matching.map(&:id)
        matching.concat @source_data_criteria.select {|dc| !existing.include?(dc.id) && force_sources.include?(dc.id)} 
      end

      matching
    end
def specific_occurrence_source_data_criteria(force_sources=nil)
      return [] if @source_data_criteria.nil?
      matching = @source_data_criteria.select {|dc| !dc.specific_occurrence.nil?}

      if force_sources
        existing = matching.map(&:id)
        matching.concat @source_data_criteria.select {|dc| !existing.include?(dc.id) && force_sources.include?(dc.id)} 
      end

      matching
    end
Get the source data criteria that are specific occurrences
 @return [Array] an array of HQMF::DataCriteria describing the data elements used by the measure that are specific occurrences