code: def set_oauth2_auth(client, secret, authorize_path, token_path, site = nil)
        FHIR.logger.info 'Configuring the client to use OpenID Connect OAuth2 authentication.'
        @use_oauth2_auth = true
        @use_basic_auth = false
        @security_headers = {}
        options = {
          site: site || @base_service_url,
          authorize_url: authorize_path,
          token_url: token_path,
          raise_errors: true
        }
        client = OAuth2::Client.new(client, secret, options)
        client.connection.proxy(proxy) unless proxy.nil?
        @client = client.client_credentials.get_token
      end
docs: Set the client to use OpenID Connect OAuth2 Authentication
   client -- client id
   secret -- client secret
   authorize_path -- absolute path of authorization endpoint
   token_path -- absolute path of token endpoint