the Chinese characters were garbled in test file

[shalom-he]

%CONTEXT
onevar = '商品'
goods = #{'title': '电脑主机', 'price': 1000}

%MESSAGES
msg = '商品'

---

DefaultContextStandardTestFieldEvaluator.getValue

            /*
             * This String -> byte[] conversion is needed because java.util.Properties 
             * did not allow using a java.io.Reader for loading properties until Java 6.
             */
            final byte[] valueAsBytes = fieldValue.getBytes("ISO-8859-1");
            final ByteArrayInputStream inputStream = new ByteArrayInputStream(valueAsBytes);

Why utf8 encoding is not supported?
My JDK version is 1.8