spring-projects/spring-data-examples — reverse-engineered prompt

Build me a Java Spring Data examples workspace that feels like a learning playground for developers who want to see how different databases work with Spring Data.

I want separate small sample apps or modules for common stores like JPA, JDBC, MongoDB, Redis, Elasticsearch, Cassandra, Neo4j, LDAP, R2DBC, REST, and web support. Each example should show the practical basics, like defining entities, repositories, saving and finding data, custom queries, pagination, projections, query by example, and reactive usage where it makes sense. Include a few more advanced examples too, like multiple data sources, security with repositories, transactions, geo spatial search, text search, vector search, pub sub, streams, and REST endpoints.

Please make it easy to run with Maven, include tests or demos for each sample, and add clear README notes explaining what each example teaches and what local services need to be running. Use current Spring Data conventions and look up current docs online if you need to.