code: public static String toHeaderValue(List<ExtensionConfig> configs) {
          if ((configs == null) || (configs.isEmpty())) {
              return null;
          }
          StringBuilder parameters = new StringBuilder();
          boolean needsDelim = false;
          for (ExtensionConfig ext : configs) {
              if (needsDelim) {
                  parameters.append(", ");
              }
              parameters.append(ext.getParameterizedName());
              needsDelim = true;
          }
          return parameters.toString();
      }
docs: Convert a list of {@link ExtensionConfig} to a header value
  
  @param configs the list of extension configs
  @return the header value (null if no configs present)