default @NotNull BossBar addViewer(final @NotNull Audience viewer) {
    viewer.showBossBar(this);
    return this;
  }
Show this bossbar to {@code viewer}.

@param viewer the viewer
@return the bossbar
@see Audience#showBossBar(BossBar)
@since 4.14.0
api/src/main/java/net/kyori/adventure/bossbar/BossBar.java