For [1] please review the proposed fix [2]. It is possible to preemptively detect a sufficient condition for when the length of the modified UTF-8 encoding of the string parameter will exceed the maximum allowed value and thereby avert any numerical overflow in incrementing the accumulator which counts the number of encoded characters.
Thanks, Brian [1] https://bugs.openjdk.java.net/browse/JDK-8219196 [2] http://cr.openjdk.java.net/~bpb/8219196/webrev.00/