In the StringUtils class it would be helpful if in the following methods, the Javadoc is improved:
I think there should be better documentation in the case where the separator string is not found in the search string: It should be explicity noted that in this case an empty string will be returned.
In the following methods:
It should be documented that if the separator is not found in the search string, the search string is returned.
I realise there are examples for both these cases, but I think that they should be separately and explicity documented as special cases. I had expected that substringAfterLast would return the original string if the separator was not found in it and this caused me some trouble.