code: @Override
      @JsonIgnore
      public Set<String> getAvailableQueryAttributes(final IPersonAttributeDaoFilter filter) {
          if (this.queryAttributeMapping == null) {
              return new HashSet<>();
          }
  
          final Set list = new HashSet(this.queryAttributeMapping.keySet());
          return list;
      }
docs: /* (non-Javadoc)
  @see org.jasig.services.persondir.IPersonAttributeDao#getAvailableQueryAttributes()