* fix #2092.

* fix #2092.

* change to Integer.compare.

* code clean.

* code clean.

This reverts commit 235a5228.

* fix #2092.

* Revert "fix #2092."

This reverts commit d8076ef2

* fix #2092. change deferredResults key toLowerCase.

* change HashMap to TreeMap.

* add DeferredResultWrapper compareTo;

* Bugfix: fix miscellaneous bugs and polish code

* Update EmbeddedApollo.java

Objects.isNull is only available from jdk 1.8 but apollo-client is targeted to jdk 1.7+, so we need to use a compatible one (#2677)

fix delete children clusters twice.

* fix setting value of property in xml is null throws NullPointerException

* fix setting null value of property in xml throws NullPointerException

This reverts commit 437026f3.

* init i18n support

* polish translations and fix some bugs introduced

* refactor app namespace duplicate message

* fix non-properties namespace display issue

* add cluster open api client
* add toString for open api dtos
* add rollback release open api

java client's long polling timeout is 90 seconds, so server side long polling timeout must be less than 90 (#2630)

fix the issue that project owner cannot manage application master even if role.manage-app-master.enabled is turned off (#2627)

openapi support create and load cluster info