* Add Light4J 1.6.x plug-in

* Add unit test for Light4J plug-in

* Add missing id to server-starter

* Remove mentions of version 1.6.x

Some local testing showed that the plugin successfully generated traces for a light4j project built with light-codegen v2.x. Therefore, there is no need for a separate plugin for v2.x and no distinction needs to be made with light4j v1.6.x.

* Update supported light4j versions

* Use ContextSnapshot to maintain trace

In a typical Light4j project, the ExceptionHandler#handleRequest is the asynchronous execution point. The flow is ExceptionHandler#handleRequest -> HttpServerExchange#dispatch -> ... -> ExceptionHandler#handleRequest. This means that handleRequest is being intercepted twice and each time a LocalSpan is created. Without handling thread propagation, the trace segment gets split up.

By saving a ContextSnapshot into the enhanced object (ExceptionHandler), we can determine if it is necessary to continue the segment.

* Update logic for span creation in trace

By default, the Light4J plugin now overrides the Undertow plugin's entry span with its own. This new entry span is created just before execution of the ExceptionHandler#handleRequest in the I/O thread. The entry span is generated here because it is considered the starting point of the Light4J handler chain.

There is now also the option to enable detailed span creation when tracing requests through Light4J. These local spans mark which middleware and business handlers are involved with handling the HTTP request to a Light4J service.

* Update skywalking version

* Update light4j version

* Fix LightInstrumentation javadoc

* Remove import violating checkstyle

This import was added from the link reference in the javadoc. The javadoc has now been changed to just reference the method name.

* Move light4j agent config property

* Sync UI

* add cassandra java driver 3.x plugin

* Fix the zookeeper plugin has many nodes in the cluster case

* support version

* Support play 2.x 

* spring_async_plugin

* fix

* fix

* fix

* fix

* format fix

* rename

* fix

* fix version

* Update SWCallable.java

* Update Supported-list.md

* Update Supported-list.md

* restore solrj-plugin

* restore solrj-plugin

* Revert SolrJ plugin.

* Remove an unexpected test case.

* Revert "Remove an unexpected test case."

This reverts commit 359990e18b0c0ae1a6e1005ff985bf237ec05619.

* Clear context.

* Fix a leak.

* new branch for solrj-plugin

* rollback and add module solrj-plugin

* preparing to pr

* to resolve reviewers' suggestions

* remove unused code

* remove unused code

* remove unused comments

* To avoid NPE

* fix typo

* Change to JRE6

* fix pom.xml merge incorrectly. and java.net.URL instead of Regex

* Using RuntimeContext instead of ThreadLocal

* To reduce unnecessary tags

* add test cases

* fix validation fail

* add solrj-plugin into component-libraries & Supported-list

* to trace all patch to avoid recheck status of span

* remove unnecessary properites

* remove unnecessary tags

* Add the config to document of setup

* merge

* merge

* Provide plugin for ShardingSphere (#2699)

* Provide plugin for ShardingSphere (#2699)

* Provide plugin for ShardingSphere (#2699)

* adjust package name (#2699)

* fix mvnw (#2699)

* revert files access permission from 644 to 755

* change the access permission from 644 to 755

* change files access permission from 644 to 755

* revert all no changes files

* feat(agent sdk): resteasy plugin

* fix(agent sdk): fix component define

* fix(agent sdk): fix file license

* fix(agent sdk): fix file license

* docs(agent sdk): add supported list

* fix(agent sdk): fix file license

* fix(agent sdk): fix response error tag

* fix(agent sdk): fix

* fix(agent sdk): adapter 3.5+

* fix(agent sdk): remove unreasonable async handling

* spring cloud gateways plugin

* Provide plugin for ShardingSphere (#1933)

Update all "incubator-skywalking" to "skywalking" ,"incubator-servicecomb-java-chassis" to "servicecomb-java-chassis" correctly, and ".gitmodules" will update at #2531 (#2548)

* vertx plugin impl

[Performance Improvement]Backend streaming thread model improvement

* Zookeeper plugin

* Support lettuce plugin

* lettuce plugin bugfix

* lettuce plugin fix license issue

* lettuce plugin fix cluster and config issue

* plugin lettuce compatible with low 5.0.x version

* lettuce plugin support version accurately describes on Supported-list.md

* plugin lettuce compatible with low 5.0.2 version

* lettuce plugin fix wrong batch method intercept point

* move lettuce to optional plugins

* fix ci issue

* fix ci issue

* Modify the description file

* Pom code optimization

* Optimization operation name

* Optimization operation name2

* plugin support redisson

* Support Gson plugin

* Support webflux and spring mvc 5 plugin

* Change instrumentation

* Change instrumentation

* fix check style

* Add support 2.1.x instrumentation

* Lock oracle and resin plugins version.

* Move resin and oracle plugin to openskywalking

* Restore submodule active.

* Add another submodule active command.

* Remove the wrong test cases in release and fix some doc issues.

* [maven-release-plugin] prepare release v6.0.0-alpha

* [maven-release-plugin] prepare for next development iteration

* Fix some doc

* Add Undertow 2.x plugin

* Undertow: Interceptor method executeRootHandler in class Connectors

* Change version number to 6.0.0-alpha-SNAPSHOT

* Enable the build of ServiceComb Java Chassis

* Updated the Supported list

Update document based on #771

Correct the English.