Based on Bethan Palmer's course - https://www.linkedin.com/learning-login/share?forceAccount=false&redirect=https%3A%2F%2Fwww.linkedin.com%2Flearning%2Fjava-design-patterns-behavioral-part-1%3Ftrk%3Dshare_ent_url%26shareId%3DfLVjhwdwTcOkFG%252B303l%252FAw%253D%253D
Each pattern has its own branch. I completed the Exercise files my self. I've looked up and added official definitions of the patterns by the gang of four.