Inside ContaineredTaskManagerParameters, since
FLINK-6217, the offHeapSize is set to the amount of memory Flink will use off-heap which will be set as the value for -XX:MaxDirectMemorySize in various cases. This does not account for any off-heap use by other components than Flink, e.g. RocksDB, other libraries, or the JVM itself.
We should add the cutoff from the CONTAINERIZED_HEAP_CUTOFF_RATIO configuration parameter to offHeapSize as implied by the description on what this parameter is there for.