6 files declare their use of ChartsDefaultSettings in Charts 5.0.x

BaseSettings.php in src/Element/BaseSettings.php

ChartBase.php in src/Plugin/chart/Library/ChartBase.php

charts.install in ./charts.install

Install and update functions for the Charts module.

ChartsDefaultSettingsTest.php in tests/src/Unit/Settings/ChartsDefaultSettingsTest.php

charts_blocks.install in modules/charts_blocks/charts_blocks.install

Install and update functions for the Charts module.

charts_highcharts.install in modules/charts_highcharts/charts_highcharts.install

Installation and update hooks for the Charts Highcharts module.