Inconsistent return type / value for `Parse.Object.getACL()`

[mtrezza]

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• I am not just asking a question.
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Issue Description

Inconsistent return type / value for Parse.Object.getACL():

• According to docs it returns Parse.ACL.
• According to code, it returns Parse.ACL | null (note: not undefined but actually null):
  

  Parse-SDK-JS/src/ParseObject.js

  Lines 1063 to 1069 in fc22640

  	getACL(): ?ParseACL {
  	const acl = this.get('ACL');
  	if (acl instanceof ParseACL) {
  	return acl;
  	}
  	return null;
  	}

Environment

Server

• Parse SDK version: 4.2.0-alpha.3

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