In Spring for Apache Pulsar, overly broad trusted-package matching in header mapper exposes JDK classes to deserialization

JsonPulsarHeaderMapper matched type headers against trusted packages using a prefix check, meaning that trusting any package implicitly trusted all of its subpackages. Additionally, an empty trusted-packages configuration fell back to trusting all packages rather than applying a safe default allow-list. Affected versions: Spring for Apache Pulsar 2.0.0 through 2.0.5; 1.2.0 through 1.2.17; 1.1.0 through 1.1.17.