Fix potential NullPointerException in addAuthorizationsForNewProcessD…

[yannaingtun]

Description:
This PR adds a null check for the process parameter in addAuthorizationsForNewProcessDefinition() to prevent potential NullPointerExceptions when this method is called with a null process.

Issue:
When the process parameter is null, calling process.getCandidateStarterUsers() or process.getCandidateStarterGroups() throws a NullPointerException, which can cause application crashes.

Fix:
Added a conditional check to verify the process parameter is not null before attempting to access its methods.

References:
Similar issue was fixed in: Activiti/Activiti@f4ad999
This implementation applies the same fix pattern to prevent null dereference

[filiphr]

@yannaingtun can you please provide a test case for this?

I do not see how this piece of code can throw a NullPointerException. Especially, because in the 2 methods before this gets called we get the process from the parsed deployment and invoke something on it without doing a null check.