spring.datasource.driver-class-name=org.postgresql.Driver
spring.datasource.url={YOUR JDBC URL}&password={YOUR SUPABASE DB PASSWORD}
spring.datasource.username={Your DB User Name From Supabase}
spring.datasource.password={Your DB Password From Supabase}
spring.jpa.show-sql=true
spring.jpa.hibernate.ddl-auto=none

You need to get the JDBC connection String from connect --> Type --> JDBC and scroll to Session Pooler to get the JDBC URL and credentials.

For step by step process please see my blog below:https://medium.com/@khan.abdulwasey99/step-by-step-process-on-how-to-connect-a-spring-boot-application-to-supabase-f1791e1d2402

Re-posting I was not aware of Stackoverflow guidelines for external blogs.