code: @Override
  	public Collection<Response> getResponses(String earliest) {
  		if(!initializedProperly) {
  			throw new IllegalStateException(getUninitializedMessage());
  		}
  		
  		Collection<Response> matchingResponses = new HashSet<>();
  		
  		for(Response response : responses) {
  			DateTime earliestDateTime = DateUtils.fromString(earliest);
  			DateTime responseDateTime = DateUtils.fromString(response.getTimestamp());
  			
  			if(earliestDateTime != null && responseDateTime != null) {
  				if(earliestDateTime.isBefore(responseDateTime)) {
  					matchingResponses.add(response);
  				}
  			}
  		}
  		
  		return responses;
  	}
docs: {@inheritDoc}