RFR: 8273329: Remove redundant null check from String.getBytes(String charsetName)

[Сергей Цыпанов]

Current implementation looks like this:

public byte[] getBytes(String charsetName)
        throws UnsupportedEncodingException {
    if (charsetName == null) throw new NullPointerException();
    return encode(lookupCharset(charsetName), coder(), value);
}

Null check seems to be redundant here because the same check of `charsetName` is done within `String.lookupCharset(String)`:

private static Charset lookupCharset(String csn) throws UnsupportedEncodingException {
    Objects.requireNonNull(csn);
    try {
        return Charset.forName(csn);
    } catch (UnsupportedCharsetException | IllegalCharsetNameException x) {
        throw new UnsupportedEncodingException(csn);
    }
}

-------------

Commit messages:
 - 8273329: Remove redundant null check from String.getBytes(String charsetName)

Changes: https://git.openjdk.java.net/jdk/pull/5361/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5361&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8273329
  Stats: 1 line in 1 file changed: 0 ins; 1 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5361.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5361/head:pull/5361

PR: https://git.openjdk.java.net/jdk/pull/5361