* rewrite http-async-client

* add unit test and document

* fix check style issue

* update test

* update doc fix ci

* fix review

* Change the buired point of block call way

* Support future way and change the operation name of span

* Add RunnableWrapper

* movement

* Fix Location

* spring aop patch #1114

* more strict check

* Allow use SkyWalking plugin to override service in Agent core.

* Fix CI.

* Remove duplicate plugin load.

* Add test cases for new plugin boot service machanism.

* commons testcase

* some ui module query testcase

* add testcase

* fix some checkStyle issue

* add some null testcase

* remove

* add license

* fix author error

* remove invalid tag @date

* add license which has been missed

* add jdk-cross-thread-plugin

* Update pom.xml

Add developer email address.

* Update pom.xml

* Update pom.xml

* Delete pom.xml.versionsBackup

* Delete pom.xml.versionsBackup

* Update pom.xml

* Delete pom.xml.versionsBackup

* Update pom.xml

* Because of key issue, system env override can't be supported.

* Override value only in supported types. Int, String, Long, Boolean.

* Provide document for TLS

* Provide direct uplink doc.

* Add namespace document.

* Provide token auth doc.

* Provide setting override document.

* Fix two typo.

* Fix more typos.

* Add client side token.

* Fix ci.

* Fix most codes of token auth at both sides.

* Add settings in config files.

* Make auth interceptor doesn't throw expcetion.

* Update AuthenticationSimpleChecker.java

* Update AuthenticationActivator.java

* Revert "Update AuthenticationActivator.java"

This reverts commit 0935f18fd6802ab84c12e0609c21ef753ff51be3.

* Merge branch 'feature/token-auth' of https://github.com/apache/incubator-skywalking into feature/token-auth

# Conflicts:
#	apm-collector/apm-collector-agent/agent-grpc/agent-grpc-provider/src/main/java/org/apache/skywalking/apm/collector/agent/grpc/provider/AuthenticationSimpleChecker.java

* Fix Auhentication token works incorrect (#1001)

* Fix Auhentication token works incorrect

* Change way to build GRPC Channel

* Response an empty header when auth fails.

Fix IPMC checks for releasing.

* Support direct server setting in agent.

* Fix format.

* Add direct_servers check (#981)

* Finish the prototype of TLS of gRPC between agent and server.

* Fix for rat check.

* Update GRPCChannelManager.java

* Update AgentModuleGRPCProvider.java

* Upgrade netty version (#971)

* Make sure end user can't start gRPC server with and without SSL in the same port.

* Update docs for alpha release

* Delete a comma.

* Update How-to-build.md

* Add data-set licenses file

* Rename LICENSES-data-set to LICENSE-data-set

* Update LICENSE

* Remove fastclick from LICENSE

* Make the git submodule command to be a maven profile plugin. Let this command not execute by default install command.

* [maven-release-plugin] prepare release apm-5.0.0-alpha

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

* Product name is not correct

* Add more documents for release.

* Change profile id.

* Add CHANGES file in distribution file.

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

This reverts commit ac815019.

* Revert "[maven-release-plugin] prepare release apm-5.0.0-alpha"

This reverts commit 095597c9.

* Add rat plugin to check dependency license and add license head into missing files.

* Fix docs.

* Exclude web ui config file.

* Next release guide.

* UI update.

* Update docs.

* Build source shell.

* [maven-release-plugin] prepare release apm-5.0.0-alpha

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

* Try to fix #886

* Try to fix ci.

* Fix a style check.

2. Setting the src span type when agent register service name.
3. Revert the topology build logic.