https://docs.oracle.com/javase/jp/8/docs/api/java/text/StringCharacterIterator.html
StringCharacterIterator (Java Platform SE 8)
java platformse
https://unicode-org.github.io/icu-docs/apidoc/dev/icu4j/com/ibm/icu/text/StringCharacterIterator.html
StringCharacterIterator (ICU4J 78)