Mark handlers as optional

[shawnmcknight]

📝 Description

PR fixes #467. A service's actions and events can be comprised from included mixins as well as the local definitions. Since the handler definitions may reside in the mixin and not the service (or vice-versa), marking the handler as a required property is incorrect. The PR marks the handler for Action and ServiceEvent as optional.

🎯 Relevant issues

#467

💎 Type of change

• Bug fix (non-breaking change which fixes an issue)

🚦 How Has This Been Tested?

Tested the type in my own repo.

🏁 Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have commented my code, particularly in hard-to-understand areas

[icebob]

Thanks

[coveralls]

Pull Request Test Coverage Report for Build 1688

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 92.279%

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Totals
Change from base Build 1674:	0.0%
Covered Lines:	4729
Relevant Lines:	4902

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💛 - Coveralls