Hey,
This seems more of an ORM question, so I’ll move it to that topic. For the available dialects, see the package: hibernate-orm/hibernate-core/src/main/java/org/hibernate/dialect at main · hibernate/hibernate-orm · GitHub. The correct name for the OracleDialect is:
org.hibernate.dialect.OracleDialect
or alternatively, see the dialect report: Supported Dialects