Allmethods config source model does not always report the full list of payment methods

[moehrenzahn]

The Magento\Payment\Model\Config\Source\Allmethods config source model does not display every available payment method.

Preconditions

1. Magento version 2.1.11, plain fresh installation

Steps to reproduce

1. Enable the Cash on Delivery payment method
2. Define a config field like this:

<field id="test" type="multiselect">
    <label>Test case for displaying all payment methods</label>
    <source_model>Magento\Payment\Model\Config\Source\Allmethods</source_model>
</field>

3. Load the config field in the Magento backend

Expected result

1. The enabled Cash on Delivery payment method should be visible in the config field multiselect

Actual result

1. The Cash On Delivery payment method is not listed in the widget

Comments

I have tracked the source of the issue down to the app/code/Magento/Payment/Helper/Data.php::getPaymentMethodList() method, which does not report the full list of payment methods when $asLabelValue = true and $withGroups = true.

The issue was apparently introduced with this commit, which does not consider that a group's $labelValues[$code]['value'] might already hold payment method information:

$labelValues[$code]['value'] = null;

This is the issue for that pull request:

• Issue: 3596. Resolve Notice with undefined index 'value' #12284

And this is the issue that prompted the problematic pull request:

• Notice: Undefined index: value in /app/code/Magento/Backend/Block/Widget/Grid/Column/Filter/Select.php on line 72 #3596

[magento-engcom-team]

@moehrenzahn, thank you for your report.
We've acknowledged the issue and added to our backlog.

[magento-engcom-team]

@moehrenzahn The issue is already fixed in 2.2.
Closing ticket for now. Please reopen if you need any further assistance with this.