class in jar declared final in 1.5 but not in 1.4

Anybody know the reason for this confusing error

I was moving a project to a new pc - where I had 1.5 (and 1.4) installed.

Extending a class in a jar-file (compiled with1.3 or earlier ) suddely malfunctioned with the error -: cannot extend final class xizzy.

I looked at the source .... it was not declared "final"

Then I remembered the installation of version 1.5

( build 1.5.0_02-b09, mixed mode, sharing)

Switch to 1.4.02 and the project compiled perfectly ?

Does anybody know anything about such behaviour ?

I simply cannot figure out this "feature".

I cannot find any bug showing this ... and I havn't yet been able to reproduce it in simple form.

[719 byte] By [esj@datavisor.dka] at [2007-10-1 16:05:11]