LANG-1003: DurationFormatUtils are not able to handle negative duration/periods. Document new behavior for negative inputs.

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/lang/trunk@1592324 13f79535-47bb-0310-9956-ffa450edef68

src/main/java/org/apache/commons/lang3/time/DurationFormatUtils.java

@@ -77,6 +77,7 @@ public class DurationFormatUtils {
      * 
      * @param durationMillis  the duration to format
      * @return the formatted duration, not null
+     * @throws java.lang.IllegalArgumentException if durationMillis is negative
      */
     public static String formatDurationHMS(final long durationMillis) {
         return formatDuration(durationMillis, "H:mm:ss.SSS");
@@ -92,6 +93,7 @@ public class DurationFormatUtils {
      * 
      * @param durationMillis  the duration to format
      * @return the formatted duration, not null
+     * @throws java.lang.IllegalArgumentException if durationMillis is negative
      */
     public static String formatDurationISO(final long durationMillis) {
         return formatDuration(durationMillis, ISO_EXTENDED_FORMAT_PATTERN, false);
@@ -106,6 +108,7 @@ public class DurationFormatUtils {
      * @param durationMillis  the duration to format
      * @param format  the way in which to format the duration, not null
      * @return the formatted duration, not null
+     * @throws java.lang.IllegalArgumentException if durationMillis is negative
      */
     public static String formatDuration(final long durationMillis, final String format) {
         return formatDuration(durationMillis, format, true);
@@ -122,10 +125,11 @@ public class DurationFormatUtils {
      * @param format  the way in which to format the duration, not null
      * @param padWithZeros  whether to pad the left hand side of numbers with 0's
      * @return the formatted duration, not null
+     * @throws java.lang.IllegalArgumentException if durationMillis is negative
      */
     public static String formatDuration(final long durationMillis, final String format, final boolean padWithZeros) {
         if(durationMillis < 0) {
-            throw new IllegalArgumentException("Duration must not be less than 0");
+            throw new IllegalArgumentException("durationMillis must not be negative");
         }
 
         final Token[] tokens = lexx(format);
@@ -166,6 +170,7 @@ public class DurationFormatUtils {
      * @param suppressLeadingZeroElements  suppresses leading 0 elements
      * @param suppressTrailingZeroElements  suppresses trailing 0 elements
      * @return the formatted text in days/hours/minutes/seconds, not null
+     * @throws java.lang.IllegalArgumentException if durationMillis is negative
      */
     public static String formatDurationWords(
         final long durationMillis,
@@ -229,6 +234,7 @@ public class DurationFormatUtils {
      * @param startMillis  the start of the duration to format
      * @param endMillis  the end of the duration to format
      * @return the formatted duration, not null
+     * @throws java.lang.IllegalArgumentException if startMillis is greater than endMillis
      */
     public static String formatPeriodISO(final long startMillis, final long endMillis) {
         return formatPeriod(startMillis, endMillis, ISO_EXTENDED_FORMAT_PATTERN, false, TimeZone.getDefault());
@@ -242,6 +248,7 @@ public class DurationFormatUtils {
      * @param endMillis  the end of the duration
      * @param format  the way in which to format the duration, not null
      * @return the formatted duration, not null
+     * @throws java.lang.IllegalArgumentException if startMillis is greater than endMillis
      */
     public static String formatPeriod(final long startMillis, final long endMillis, final String format) {
         return formatPeriod(startMillis, endMillis, format, true, TimeZone.getDefault());
@@ -269,11 +276,12 @@ public class DurationFormatUtils {
      * @param padWithZeros  whether to pad the left hand side of numbers with 0's
      * @param timezone  the millis are defined in
      * @return the formatted duration, not null
+     * @throws java.lang.IllegalArgumentException if startMillis is greater than endMillis
      */
     public static String formatPeriod(final long startMillis, final long endMillis, final String format, final boolean padWithZeros, 
             final TimeZone timezone) {
         if(startMillis > endMillis) {
-            throw new IllegalArgumentException("endMillis must be greater than startMillis");
+            throw new IllegalArgumentException("startMillis must not be greater than endMillis");
         }
 
         // Used to optimise for differences under 28 days and