関連ワード:  java stream findfirst orelse    java stream findfirst orelseget    java stream findfirst orelsethrow    java stream findfirst orelse example    java stream findfirst orelse null    java stream findfirst map orelse    java stream findfirst ifpresent orelse    java 8 stream filter findfirst orelse example    java stream filter findfirst or else    java stream findfirst or else throw exception