A DESCRIPTION OF THE PROBLEM :
The documentation for Linebreak Matcher \R states that it is equivalent to a specific pattern. However if we substitute that equivalent pattern into a regex, it can give different results.
See the following Stack Overflow question and answer for details--
http://stackoverflow.com/q/42474596/7098259

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
...is equivalent to (?<!\u000D\u000A|[\u000A\u000B\u000C\u000D\u0085\u2028\u2029])
ACTUAL -
...is equivalent to \u000D\u000A|[\u000A\u000B\u000C\u000D\u0085\u2028\u2029]

URL OF FAULTY DOCUMENTATION :
https://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html