code: @SuppressWarnings("unchecked")
  	public <T extends Filter> T getFirstFilterForField(String field) {
  		for (Filter filter : this.filters) {
  			if (filter.getField().equals(field)) {
  				return (T) filter;
  			}
  		}
  		return null;
  	}
docs: Returns the first filter for the field.
  
  @param field name of the field
  @return the first filter for the field. Null if not filter exists.