On line:

https://github.com/testcontainers/testcontainers-java/blob/master/core/src/main/java/org/testcontainers/containers/GenericContainer.java#L136-L139

A random network alias is assigned during field initialization time, this ALWAYS prevents the computed hash from matching, unless one calls container.getNetworkAliases().clear() before adding their own network alias with .withNetworkAliases("some static value").

I propose that the default behaviour to allocate a random network alias be changed to happen lazily and when no other explictly specified network alias is set.

And also perhaps print a warning/error when no explict network alias is defined and .withReuse(true) is used.