Update gradle and java to 17

What does this MR do (summary)?

Keep java versions in line with other projects

Screenshots

What changes have you made (detailed)?

Does this MR meet the acceptance criteria?

• The main application was run to make sure the server still runs without errors.
• Tests were written to verify the behaviour of this code.
• Javadoc and other comments were added to make the code understandable.
• The code adheres to the style guidelines.