Hibernate.ddl-auto: update

I have taken hibernate.ddl-auto :update option but it is not updating in the db.
The yml configuration is given below:
jpa:
database-platform: org.hibernate.dialect.Oracle10gDialect
show-sql: true
generate-ddl: true
hibernate.ddl-auto: update
properties:
hibernate:
cache:
use_second_level_cache: false
use_query_cache: false
generate_statistics: false.

Can you please give some pointers over it?