code: public String getHeader(@NotNull final String name, String defaultValue) {
          if (headers().contains(name)) {
              return getHeader(name);
          } else {
              return defaultValue;
          }
      }
docs: Allow getting headers in a generified way and return defaultValue if the key does not exist.
  
  @param name The key to get
  @param defaultValue value returned when the key does not exist
  @return {String} The found object