Notes

From my perspective according to position you need to know following areas:
1) SOA: what is it? Why we need it (including customer perspective)? How we can do that?
2) HTTP: definition, request + response (be able to describe basic example of req/resp), header, cookie, session, request types, response code groups, ways how to pass data into request.
3) REST: definition, why we need it?, CRUD mapping on HTTP, error handling, caching, HATEOAS, URL mapping patterns (inc. parameters).
4) Agile (scrum): agile principles, difference vs waterfall; Scrum: roles, story requirements, definition of done, interaction (meeting) types.
5) Java 8: data types, memory model, multithreading, collections.
6) Spring boot: how it works? Why it helpful for services development? Spring boot responsibility area.
7) JPA (Hibernate): model configuration, relations mapping (1-1, 1-n, n-n), enum mapping, inheritance/extending (3 ways), transactions, batching, CRUD, spring-data.
8) H2: understand how it can be used for testing.
9) Liquidbase: definition, create mapping, migration, be able to rollback it.
10) Maven: build lifecycle, goals, roles.
11) CI/CD
12) Docker

I've bolded all high priority skills which you need to go over first.
Please, (where is possible) you need to be able to provide at least trivial examples (use cases).