Add missing @throws javadoc

sop-java/src/main/java/sop/util/UTCUtil.java

@@ -33,6 +33,7 @@ public class UTCUtil {
      *
      * @param dateString string
      * @return date
+     * @throws ParseException if the date string is malformed and cannot be parsed
      */
     @Nonnull
     public static Date parseUTCDate(String dateString) throws ParseException {

sop-java/src/main/java/sop/util/UTF8Util.java

@@ -26,6 +26,7 @@ public class UTF8Util {
      * @param data utf-8 encoded bytes
      *
      * @return decoded string
+     * @throws CharacterCodingException if the input data does not resemble UTF8
      */
     public static String decodeUTF8(byte[] data)
             throws CharacterCodingException {