https://hackmd.io/@Z8SXmKIDQJW5D6zTi_T89w/B1KV8og-O
https://www.notion.so/Struts-2-20210110-52fb7fb0fd004f969346fe9511c99943
https://www.notion.so/Struts-2-Framework-2-6585bcddc0ab44f28f0be8fea1499e29
https://www.notion.so/Struts-2-Framework-3-b88b4195e8cd4eb98be70dd44c2ad0d8
https://www.evernote.com/shard/s422/nl/216468519/c9473607-0477-4b75-ba9f-4866fc4bc4f9