code: public int getNumberOfDocs(String field) {
      if (fieldReferences.containsKey(field)) {
        FieldReferences fr = fieldReferences.get(field);
        return fr.numberOfDocs;
      } else {
        return 0;
      }
    }
docs: Gets the number of docs.
  
  @param field
  the field
  @return the number of docs