* process instance variables initialization

* improve exception message

* Add activiti-spring-process-extensions dependency to parent pom

* Fix failing tests

* Fix transitive dependency

* check types of variables on proc start

* Rebasing with develop

* make variable types and their validation extensible

* add test specifically for loading of extensions

* simplify names and add comments

* add slf4j

* initial refactoring for candidateUsers and Groups

* updating api and common version

Initial work on conformance tests at the spring boot app level:
Fixes https://github.com/Activiti/Activiti/issues/2128

* fix: refactor activiti-core-dependencies-tests module

* fix: (mergify) add do-not-merge label condition

* fix: move activiti-dependencies-parent to root pom

* Update .mergify.yml

* feat: add activiti-core-dependencies-tests module

* revert: set activiti-build.version to 7.0.41

* Update .mergify.yml

* fix: enforce same parent version dependency

* fix: add -DenforceFail=false property to control enforce fail behavior

* fix(version): update org.activiti.core.common:activiti-core-common-dependencies to 7.0.21

* Add missing import

* fix(version): update org.activiti.core.common:activiti-core-common-dependencies to 7.0.19

* Trigger CI pipelines

* trigger another CI buld

* trigger build

* fix(version): update org.activiti.build:activiti-parent to 7.0.41

* fix groovy dependency which is missing from SB 2.1

* replace containsExactly for isEqualTo