in invoker/core/src/main/java/com/google/cloud/functions/invoker/http/HttpRequestImpl.java [151:159]
public Optional<String> getCharacterEncoding() {
String contentType = getContentType().orElse(null);
if (contentType == null) {
return Optional.empty();
}
Pattern charsetPattern = Pattern.compile("(?i).*;\\s*charset\\s*=([^;\\s]*)\\s*(;|$)");
Matcher matcher = charsetPattern.matcher(contentType);
return matcher.matches() ? Optional.of(matcher.group(1)) : Optional.empty();
}