" " appears a couple times in the docs for StringBuilder.subSequence:
https://docs.oracle.com/en/java/javase/15/docs/api/java.base/java/lang/StringBuilder.html#subSequence(int,int)
https://docs.oracle.com/en/java/javase/15/docs/api/java.base/java/lang/StringBuilder.html#subSequence(int,int)