https://maven.fabricmc.net/docs/yarn-1.21.1+build.1/net/minecraft/client/realms/gui/screen/RealmsMainScreen.NotificationButtonWidget.html
RealmsMainScreen.NotificationButtonWidget (yarn 1.21.1+build.1 API)
declaration: package: net.minecraft.client.realms.gui.screen, class: RealmsMainScreen, class: NotificationButtonWidget
yarnbuildapi