code: public static Predicate<GitHubServerConfig> withHost(final String host) {
          return new NullSafePredicate<GitHubServerConfig>() {
              @Override
              protected boolean applyNullSafe(@Nonnull GitHubServerConfig github) {
                  return defaultIfEmpty(github.getApiUrl(), GITHUB_URL).contains(host);
              }
          };
      }
docs: Returns true if given host is part of stored (or default if blank) api url
  
  For example:
  withHost(api.github.com).apply(config for ~empty~) = true
  withHost(api.github.com).apply(config for api.github.com) = true
  withHost(api.github.com).apply(config for github.company.com) = false
  
  @param host host to find in api url
  
  @return predicate to match against {@link GitHubServerConfig}