Using the "testLegacy" prefix to mark tests as legacy is deprecated

PHPUnit 6.5.14 is failing with a warning due to Drupal\Tests\address\Kernel\Plugin\migrate\field\AddressFieldTest. The problem is that it is translating "testLegacyPlugin" to be a legacy test method, not the actual legacy plugin.

This is the failure locally

<?xml version="1.0"?>
<testsuite>
    <testcase classname="Drupal\Tests\address\Kernel\Plugin\migrate\field\AddressFieldTest"
              name="Drupal\Tests\address\Kernel\Plugin\migrate\field\AddressFieldTest">
        <failure type="failure" message="Other">PHPunit Test failed to complete; Error: PHPUnit 6.5.14 by Sebastian
            Bergmann and contributors.&lt;br /&gt;
            &lt;br /&gt;
            Testing Drupal\Tests\address\Kernel\Plugin\migrate\field\AddressFieldTest
            .W 2 / 2 (100%)&lt;br /&gt;
            &lt;br /&gt;
            Time: 4.71 seconds, Memory: 10.00MB&lt;br /&gt;
            &lt;br /&gt;
            There was 1 warning:&lt;br /&gt;
            &lt;br /&gt;
            1) Drupal\Tests\address\Kernel\Plugin\migrate\field\AddressFieldTest::testLegacyPlugin&lt;br /&gt;
            Using the &amp;quot;testLegacy&amp;quot; prefix to mark tests as legacy is deprecated since version 3.3 and
            will be removed in 4.0. Use the &amp;quot;@group legacy&amp;quot; notation instead to add the test to the
            legacy group.&lt;br /&gt;
            &lt;br /&gt;
            WARNINGS!&lt;br /&gt;
            Tests: 2, Assertions: 6, Warnings: 1.&lt;br /&gt;
        </failure>
    </testcase>
</testsuite>