Minor Description
In the Javadoc for StringUtils.splitPreserveAllTokens(String, char) there are a couple of mistakes. I didn't check for similar mistakes in the similar functions with different signatures.
StringUtils.splitPreserveAllTokens("a..b.c", '.') = ["a", "b", "c"]
should read
StringUtils.splitPreserveAllTokens("a..b.c", '.') = ["a", "", "b", "c"]
These two lines have the same input giving different outputs. I think that the input string on the second call should be "a b c ".
StringUtils.splitPreserveAllTokens("a b c ", ' ') = ["a", "b", "c", ""]
StringUtils.splitPreserveAllTokens("a b c ", ' ') = ["a", "b", "c", "", ""]