Co-authored-by: 吴晟 Wu Sheng <wu.sheng@foxmail.com>

* Fix JdkObsolete issue

* Fix code style
Co-authored-by: 吴晟 Wu Sheng <wu.sheng@foxmail.com>

Inner class is non-static but does not reference enclosing class

ref: https://errorprone.info/bugpattern/ClassCanBeStaticCo-authored-by: 吴晟 Wu Sheng <wu.sheng@foxmail.com>

Non-exhaustive switch; either add a default or handle the remaining cases: VALUE, UNKNOWN
Co-authored-by: 吴晟 Wu Sheng <wu.sheng@foxmail.com>

ref: https://errorprone.info/bugpattern/GetClassOnEnum

* Upgrade dependencies and make the JDK11 compiling passed.

* Update license and fix license check file.

* Add CI for JDK11 compiling.

* Update doc.

* Polish comments of the meter at the agent side.

* Fix code style.

* Add a muse configuration file

A muse configuration and file is necessary to educate the MuseDev CI
system on how to build Skywalking.

* Exclude .muse/* files from license check

Co-authored-by: 吴晟 Wu Sheng <wu.sheng@foxmail.com>

* modify witness class

* modify witness class & add test case

* replace DB_STATEMENT to DB_BIND_VARIABLES & remove executeMethod prefix

* fix ci
Co-authored-by: 吴晟 Wu Sheng <wu.sheng@foxmail.com>

Co-authored-by: 吴晟 Wu Sheng <wu.sheng@foxmail.com>

Co-authored-by: 吴晟 Wu Sheng <wu.sheng@foxmail.com>

* Fix typo and add comments.

* Fix comment.

* support build single module

* enforce maven version must greater than 3.6

* update build doc to support maven3.6+

* Correct the module missing check.
* Don't check the docker compose version, as the GitHub installed 3.x in default.

* Parse tls mode from als
Signed-off-by: NGao Hongtao <hanahmily@gmail.com>

* Polish code
Signed-off-by: NGao Hongtao <hanahmily@gmail.com>

Co-authored-by: 吴晟 Wu Sheng <wu.sheng@foxmail.com>