Tutorials/Wither rose farming

Wither rose farming is the process of trapping withers and using them to kill mobs and make them drop wither roses.

Why bother?
O̶n̶l̶y̶ ̶w̶i̶t̶h̶e̶r̶ ̶s̶k̶e̶l̶e̶t̶o̶n̶s̶ ̶c̶a̶n̶ ̶s̶p̶a̶w̶n̶ ̶i̶n̶ ̶w̶i̶t̶h̶e̶r̶ ̶r̶o̶s̶e̶s̶,̶ ̶s̶o̶ ̶t̶h̶a̶t̶ ̶m̶a̶k̶e̶s̶ ̶i̶t̶ ̶i̶d̶e̶a̶l̶ ̶f̶o̶r̶ ̶w̶i̶t̶h̶e̶r̶ ̶s̶k̶e̶l̶e̶t̶o̶n̶ ̶f̶a̶r̶m̶s̶.̶ (As of Minecraft 20w19a they do not allow wither skeletons to spawn.) They do damage to entities but not items, so it can be used in other farms as a killing mechanism.

JC Playz's design (Bedrock 1.17)
This design is both a wither killer and wither rose farm.