src/vs/workbench/common/editor/sideBySideEditorInput.ts/SideBySideEditorInput/getLabelExtraClasses
class SideBySideEditorInput:	override getLabelExtraClasses(): string[] {
		if (this.hasIdenticalSides) {
			return this.primary.getLabelExtraClasses();
		}

		return super.getLabelExtraClasses();
	}