ChecksumCalculator does the following in getSha1:
This isn't using the right length, because configValue.length() is a length in characters, not bytes. This will lead to the wrong length being used for any strings that contain characters that aren't encoded in a single byte.
Additionally, I believe that this class can be used to compute checksums on strings that fall outside the ISO_8859_1 character set, so UTF_8 would be a better choice.
I ran into this when defining a test property that contained Cyrillic characters and emojis.