private void expect(byte[] expected) {
        for (byte b : expected) {
            if ( ! skip(b)) {
                in.fail("Unexpected " + characterToReadableString(c));
                return;
            }
        }
    }
Decode bytes as a UTF-8 JSON into Slime, or throw {@link JsonParseException} on invalid JSON.
vespajlib/src/main/java/com/yahoo/slime/JsonDecoder.java