関連ワード:  default interface in java 8    default functional interface in java 8    default method in interface java 8    default method in interface java 8 example    default vs static method in interface java 8    default and static method in interface java 8    default keyword in java 8 interface    default and static methods in interface java 8 example    multiple default method in interface java 8    use of default method in interface java 8