Spring Boot 3.5: A lot of smaller stuff: SSL support for service connections, multiline environment variable support, annotations to register Servlet/Filters, ...
Spring Boot 3.4: Structured Logging
Spring Boot 3.3: Class Data Sharing (CDS), Software Bill of Materials (SBOM)
Spring Boot 3.2: Virtual threads, SSL hot reload
Spring Boot 3.1: Docker Compose and Testcontainers support
Spring Boot 3.0: GraalVM's native image support, Observability