Replace erroneous usage of unsData method

[t-richards]

Description (*)

This pull request replaces incorrect usages of the magic unsData method. Note that there is nothing inherently wrong with magic methods like unsData(), but calling the uns or has variants with any arguments is a mistake.

For example,

// Syntactically correct, but probably doesn't do what you think it does
$object->unsData('_form_key');
//          ^^^^
// __call method takes the key from the method name, not from the method argument

The above statement is functionally equivalent to the following code:

// We're unsetting the "data" key which is not what we wanted.
// This usually results in no data being unset from the object 
$object->unsetData('data');

Since the unsData method is being called with an argument, it is almost certainly the case that the original author(s) intended to use the unsetData method instead.

// Corrected code
$object->unsetData('_form_key');

Fixed Issues (if relevant)

N/A

Manual testing scenarios (*)

1. Expect for all test results to stay exactly the same.
2. If any test results change, then the tests should be re-examined for correctness.

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[magento-cicd2]

All committers have signed the CLA.

[magento-engcom-team]

Hi @t-richards. Thank you for your contribution
Here is some useful tips how you can test your changes using Magento test environment.
Add the comment under your pull request to deploy test or vanilla Magento instance:

• @magento-engcom-team give me test instance - deploy test instance based on PR changes
• @magento-engcom-team give me $VERSION instance - deploy vanilla Magento instance

For more details, please, review the Magento Contributor Assistant documentation

[orlangur]

@t-richards nice catch! Need to check if there are similar occurrences in non-public code.

[slavvka]

@orlangur Probably it makes sense to add some logic which checks if uns***() method is called with arguments? And preferably to fallback to unset('***') method?

[slavvka]

@orlangur and I see no reason on holding this PR on since it is a fix anyway :)

[orlangur]

No such occurrences in B2B/EE code.

[orlangur]

@slavvka I would rather throw an InvalidArgumentException but this error is quite rare thus I don't think we really need to change DataObject.

[magento-engcom-team]

Hi @orlangur, thank you for the review.
ENGCOM-3401 has been created to process this Pull Request

[magento-engcom-team]

Hi @t-richards. Thank you for your contribution.
We will aim to release these changes as part of 2.3.1.
Please check the release notes for final confirmation.