code: public Conditionals ifModifiedSince(LocalDateTime time) {
          Preconditions.checkArgument(match.isEmpty(), String.format(ERROR_MESSAGE, HeaderConstants.IF_MODIFIED_SINCE, HeaderConstants.IF_MATCH));
          Preconditions.checkArgument(!unModifiedSince.isPresent(), String.format(ERROR_MESSAGE, HeaderConstants.IF_MODIFIED_SINCE, HeaderConstants.IF_UNMODIFIED_SINCE));
          time = time.withNano(0);
          return new Conditionals(empty(), noneMatch, Optional.of(time), Optional.empty());
      }
docs: You should use the server's time here. Otherwise you might get unexpected results.
  
  The typical use case is:
  
  
  <pre>
  HTTPResponse response = ....
  HTTPRequest request = createRequest();
  request = request.conditionals(new Conditionals().ifModifiedSince(response.getLastModified());
  </pre>
  
  @param time the time to check.
  @return the conditionals with the If-Modified-Since date set.