Pattern.splitAsStream JavaDoc doubt

[Tagir F. Valeev]

Hello!

Currently Pattern.splitAsStream JavaDoc says [1]:

 * <p> If the input sequence is mutable, it must remain constant during the
 * execution of the terminal stream operation.  Otherwise, the result of the
 * terminal stream operation is undefined.

However in reality the sequence must remain constant from the stream
creation till the end of the terminal operation. Let's check:

public static void main(String[] args) {
    StringBuilder sb = new StringBuilder("a,b,c,d,e");
    Stream<String> stream = Pattern.compile(",").splitAsStream(sb);
    // Modify the CharSequence after stream creation
    sb.setLength(3);
    // During the terminal operation it remains constant
    stream.forEach(System.out::println);
}

The result is:
a
Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 3
    at java.lang.AbstractStringBuilder.charAt(AbstractStringBuilder.java:210)
    at java.lang.StringBuilder.charAt(StringBuilder.java:76)
...

So I feel either the JavaDoc or the implementation should be changed.
Changing the implementation to fit the JavaDoc is quite simple. See
the attached pattern-patch.txt and pattern-patch2.txt for two possible
alternatives.

What do you think?

With best regards,
Tagir Valeev.

[1] http://hg.openjdk.java.net/jdk9/dev/jdk/file/3c3a5343044c/src/java.base/share/classes/java/util/regex/Pattern.java#l5803
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