jodd-core/src/main/java/jodd/util/StringUtil.java
public static char detectQuoteChar(final String str) {
		if (str.length() < 2) {
			return 0;
		}

		final char c = str.charAt(0);

		if (c != str.charAt(str.length() - 1)) {
			return 0;
		}

		if (c == '\'' || c == '"' || c == '`') {
			return c;
		}

		return 0;
	}
public static char detectQuoteChar(final String str) {
		if (str.length() < 2) {
			return 0;
		}

		final char c = str.charAt(0);

		if (c != str.charAt(str.length() - 1)) {
			return 0;
		}

		if (c == '\'' || c == '"' || c == '`') {
			return c;
		}

		return 0;
	}
Detects quote character or return 0.