public static boolean isBlank(final String str) {
        if (str == null) {
            return true;
        } else if (str.isEmpty()) {
            return true;
        } else {
            return str.chars()
                    .allMatch(Character::isWhitespace);
        }
    }
GWT doesn't support {@link String#isBlank()}

@return True if str is null, empty or contains only whitespace.
stroom-util-shared/src/main/java/stroom/util/shared/StringUtil.java