code: public ResponseBuilder standardHeaders(final ResponseBuilder builder) {
  
          // Standard HTTP Headers
          builder.lastModified(from(getResource().getModified())).header(VARY, ACCEPT);
  
          final IRI model;
  
          if (getRequest().getExt() == null || DESCRIPTION.equals(getRequest().getExt())) {
              if (syntax != null) {
                  builder.header(VARY, PREFER);
                  builder.type(syntax.mediaType());
              }
  
              model = getResource().getBinaryMetadata().isPresent() && syntax != null
                  ? LDP.RDFSource : getResource().getInteractionModel();
              // Link headers from User data
              getResource().getExtraLinkRelations().collect(toMap(Entry::getKey, Entry::getValue))
                  .entrySet().forEach(entry -> builder.link(entry.getKey(), join(" ", entry.getValue())));
          } else {
              model = LDP.RDFSource;
          }
  
          // Add LDP-required headers
          addLdpHeaders(builder, model);
  
          // Memento-related headers
          addMementoHeaders(builder);
  
          return builder;
      }
docs: Get the standard headers.
  @param builder the response builder
  @return the response builder