From 396df7d7adeee8e00a1ee1eac380b0c5c8368a7f Mon Sep 17 00:00:00 2001
From: Ben Fortuna <bfortuna@odecee.com.au>
Date: Mon, 20 Jul 2020 11:24:58 +1000
Subject: [PATCH] Support negation of temporal amount instances

---
 .../net/fortuna/ical4j/groovy/PeriodExtension.groovy   | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/main/groovy/net/fortuna/ical4j/groovy/PeriodExtension.groovy b/src/main/groovy/net/fortuna/ical4j/groovy/PeriodExtension.groovy
index 0697d3d88..965690b2a 100644
--- a/src/main/groovy/net/fortuna/ical4j/groovy/PeriodExtension.groovy
+++ b/src/main/groovy/net/fortuna/ical4j/groovy/PeriodExtension.groovy
@@ -34,6 +34,8 @@ package net.fortuna.ical4j.groovy
 import net.fortuna.ical4j.model.Period
 import net.fortuna.ical4j.model.PeriodList
 
+import java.time.Duration
+
 class PeriodExtension {
 	static Period plus(Period self, Period period) {
 		self.add(period)
@@ -42,4 +44,12 @@ class PeriodExtension {
 	static PeriodList minus(Period self, Period period) {
 		self.subtract(period)
 	}
+
+	static java.time.Period negative(java.time.Period self) {
+		self.negated()
+	}
+
+	static Duration negative(Duration self) {
+		self.negated()
+	}
 }