@throws nullpointerexception if the input parameter is null
@return the given reader or a new {@link bufferedreader} for the given reader
@param size the buffer size, if a new bufferedreader is created.
@param reader the reader to wrap or return (not null)
file : https_github_com_apache_commons-io_git/src/main/java/org/apache/commons/io/IOUtils.java