Custom 

The Custom trigger is used to show the indicators in the TYPO3 backend for custom conditions.

ext_localconf.php 
\KonradMichalik\Typo3EnvironmentIndicator\Configuration\Handler::addIndicator(
    triggers: [
        new \KonradMichalik\Typo3EnvironmentIndicator\Configuration\Trigger\Custom(
            function () {
                return true;
            }
        ),
        new \KonradMichalik\Typo3EnvironmentIndicator\Configuration\Trigger\Custom('\YourExtension\YourClass::yourMethod'),
    ],
    indicators: [
        new \KonradMichalik\Typo3EnvironmentIndicator\Configuration\Indicator\Backend\Topbar([
            'color' => '#00ACC1',
        ]),
    ]
);
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The configuration supports a callable function, which is executed to determine if the indicator should be shown. The function should return a boolean value. The function can also be a closure or an anonymous function.

When using a string reference, it must follow the format ClassName::methodName (without parentheses). The referenced method must be public and static. If the method throws an exception during execution, the trigger will return false.