StreamConstants.html#PROTOCOL_VERSION_1" title="class or interface in java.io" class="external-link">PROTOCOL_VERSION_1</a>, <a href="https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/io/ObjectStreamConstants.html#PROTOCOL_VERSION_2" title="class or interface in java.io" class="external-link">PROTOCOL_VERSION_2</a>, <a href="https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/io/ObjectStreamConstants.html#SC_BLOCK_DATA" title="class or interface in java.io" class="external-link