Description of problem:
If human task is assigned to group(Group1) and user "User1" is part of Group1. User1 is able to claim and complete human task through console without any issue. But it fails with permission denied exception when we try to claim task through Remote REST API. It fails with same exception with /execute endpoint as well.

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
1. Create process with Human Task which is assigned to Group.
2. Start process and try to claim Task which is part of assigned Group, through Remote REST API or through /execute endpoint.
3. It fails with exception:
~~~
PermissionDeniedException thrown with message 'User '[UserImpl:'User1']' does not have permissions to execute operation 'Claim' on task id 15
~~~

Actual results:
User is not able to claim task through Remote REST API or through /execute endpoint.

Expected results:
User should be able to claim task through Remote REST API or through /execute endpoint.

Additional info: