* Make sure all document images ref from our Apache website.

* Change the statement.

* Update README.md

* Update powered-by.md

* Fixed an error that took a non-protocol uri string as a java.net.URL construct parameter.

* Fixed an error that took a non-protocol uri string as a java.net.URL construct parameter.

* Fixed checkstyle error.

* Set dist bin tar with -bin in the final name.

* Change dockerfile and makefile

* Update powered-by.md

* Update powered-by.md

* Update powered-by.md

fixed CPU UsagePercent Error
The cpu usage storage longitude should be one percent, not one in ten thousand. When the storage unit is one ten thousandth, as long as the usage rate does not exceed 100%. Stored values are less than one. When the current query is forced to be converted to a long type, it will always be 0. This is not correct.

* Add Database source

* Add DatabaseSource source and database_* script for oal

* Enable Database_Indicator

* Add file license

* Rename DatabaseService to ClientDatabase. In the future, we may have real database server monitoring.

* Add query database from H2

* refactor

* update submodule

* refactor

* Fix style

* Fix: unknown tag error

* fix checkstyle

* 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

* Optimize the grpc channel management.

* Rename old version concepts

* Notify when rebuild connection.

* Remove notify in new channel created.

* Remove println.

* Refactor register and reduce the lock time.

* Refactor es id generation mechanism.

* Wrong commit place.

for issue#2196

* fix gRPCHost

* fix gRPCHost

* 1. Sleep 500 milliseconds after a batch re-call finish.
2. Re-create register lock index when the system property named debug is setting.
3. Get the register inventory before lock to avoid increment the sequence but not use.
4. Return the exchange flag after all the references and spans in one segment parsed to reduce the number of segment parse.
5. Put the not exchanged segment into a collection then try to exchange no more than 10 times because of the exchange is asynchronous.
6. Cache the segment object to avoid repeated deserialization.

#2185

* #2185
1. Sleep 500 milliseconds after a batch re-call finish.
2. Re-create register lock index when the system property named debug is setting.
3. Get the register inventory before lock to avoid increment the sequence but not use.

* fix no language attr value in mesh (#2182)

* Fixed the inventory register lock invalid bug. (#2184)

* #2183

Merge commit into master.

* Make the h2 register lock same as mysql.

* Fix #2186

* #2183

Merge commit into master.

* Make the h2 register lock same as mysql.

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

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

correct spelling error.

* Update trace-mode-grafana.json

Update heatmap expression

* Update trace-mode-grafana.json

* Update mesh-mode-grafana.json

fix bugs for more than one instance

* Update mesh-mode-grafana.json

Fix heatmap

* fixed  the index name to format name in logs

* modify the log level from info to debug

* Update ReferenceIdExchanger.java

Change comments of codes.

* 🎉 PHP agent

* Update powered-by.md

Change user list order

* Refactor service instance inventory to properties based entity.

* Fix a bug and refactor properties update.

* support overview-cn.md translation

* update overview-cn.md translation

* update fix error statement problem

* update fix error statement