Allow triggering an environment only when multiple specified environments run with success

Problem

We can trigger an environment when another environment is successfully run, but we can't trigger it based on more than one environment.
Let's suppose the following scenario:

• Env1 is triggered when a Plan build x successfully finishes
• Env2 is also triggered when Plan build x successfully finishes
• Env1 and Env 2 will run in parallel due to this configuration
• Env3 should run only when Env1 and Env2 finishes with success

This scenario is not achievable with the current implementation of Bamboo. It means that we can define a sequence of environments to run one after another, but we can't run some of them in parallel. If we try that we will lose the ability to run the chain of events that connect them.

Suggested solution

Allow triggers to have multiple previous environments. The trigger should provide the option to check if all of them succeeded before triggering the current environment.