Typos around @code javadoc tag usage

One mistake is to use regular parenthesis, e.g.:

- * if (@code options} contains an element that is not a
+ * if {@code options} contains an element that is not a

- * and optionally (@code NANO_OF_SECOND). The value of {@code INSTANT_SECONDS}
+ * and optionally {@code NANO_OF_SECOND}. The value of {@code INSTANT_SECONDS}