带有SHAwithECDSA的Java Signature.sign（）在多次运行中产生不同的结果

I am trying to sign a byte stream which does not change with a private key that does not change either, using the SHAwithECDSA. This should produce the same result, no matter how often you run the code. However, I experience some randomness which I can't explain as the resulting output changes with every run. I am trying to sign a byte stream which does no