The unsafe off-heap in FLINK-13985 was implemented by hacking into a private constructor of java.nio.DirectByteBuffer. This causes undesirable warnings in Java 11:
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.apache.flink.core.memory.MemoryUtils (file:/C:/Development/repos/flink/flink-core/target/classes/) to constructor java.nio.DirectByteBuffer(long,int)
WARNING: Please consider reporting this to the maintainers of org.apache.flink.core.memory.MemoryUtils
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
We should look into this, confirm that it is harmless and try to silence it to avoid confusion for users.