It was optimistic because Java came out long before 64 bit systems were common.
C and C++ usually do that too.
Interestingly, I can't find any information on Google about this, but ChatGPT does support this. Unfortunately all the primary sources it gave me are for docs that no longer exist on the web. The Wayback machine was no help. The old web is dead :(
Or perhaps that never existed. It's well known that ChatGPT often hallucinates non-existing references (see for instance the discussion at https://news.ycombinator.com/item?id=33841672).
It's unclear whether it's actually a 64-bit build. Did Windows even have a 64-bit userspace on Alpha, or was it all ILP32?
Anyway, it's not really possible to implement the Java memory model on Alpha: https://www.cs.umd.edu/~pugh/java/memoryModel/AlphaReorderin... So it's not really a natural target for Java code.
Ouch!