I had the same question. It seems to be in bytes. You can confirm this by writing a simple java program that repeats adding material to the list and then running it using "java -Xmx2m -XX: + HeapDumpOnOutOfMemoryError" to make the most of its 2M heap and unload the heap when it is full, then upload the hprof file to the verification tool.
Haixin tie
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