我们使用apache（2.4.41）Web服务器作为运行自实现负载平衡器的tomcat（8.5）的反向代理。ApacheWebServer负责前端tls工作，并通过ajp（mod_proxy_ajp）与tomcat进行对话。在负载平衡器中，我们使用request.getattributenames（）计算请求属性。在一段时间内，会出现带有以下键的空请求属性：
org.apache.tomcat.util.net.secure\u协议\u版本
javax.servlet.request.key\u大小
javax.servlet.request.cipher\u套件
javax.servlet.request.ssl\u会话\u id
我阅读了文档和源代码，但不明白为什么这些空属性仍然存在于请求中。根据tomcat请求中getattributenames（）的javadoc，大多数特定于tls的属性不应通过此方法获取：

/**
 * Return the names of all request attributes for this Request, or an
 * empty <code>Enumeration</code> if there are none. Note that the attribute
 * names returned will only be those for the attributes set via
 * {@link #setAttribute(String, Object)}. Tomcat internal attributes will
 * not be included although they are accessible via
 * {@link #getAttribute(String)}. The Tomcat internal attributes include:
 * <ul>
 * <li>{@link Globals#DISPATCHER_TYPE_ATTR}</li>
 * <li>{@link Globals#DISPATCHER_REQUEST_PATH_ATTR}</li>
 * <li>{@link Globals#ASYNC_SUPPORTED_ATTR}</li>
 * <li>{@link Globals#CERTIFICATES_ATTR} (SSL connections only)</li>
 * <li>{@link Globals#CIPHER_SUITE_ATTR} (SSL connections only)</li>
 * <li>{@link Globals#KEY_SIZE_ATTR} (SSL connections only)</li>
 * <li>{@link Globals#SSL_SESSION_ID_ATTR} (SSL connections only)</li>
 * <li>{@link Globals#SSL_SESSION_MGR_ATTR} (SSL connections only)</li>
 * <li>{@link Globals#PARAMETER_PARSE_FAILED_ATTR}</li>
 * </ul>
 * The underlying connector may also expose request attributes. These all
 * have names starting with "org.apache.tomcat" and include:
 * <ul>
 * <li>{@link Globals#SENDFILE_SUPPORTED_ATTR}</li>
 * </ul>
 * Connector implementations may return some, all or none of these
 * attributes and may also support additional attributes.
 *
 * @return the attribute names enumeration
 */
 @Override
 public Enumeration<String> getAttributeNames() {

也许有些人能对此有所启发。提前谢谢！