Add minus operator to DatePeriod and DateTimePeriod

Author: PeterAttardo

core/common/src/DateTimePeriod.kt

@@ -448,6 +448,17 @@ public operator fun DateTimePeriod.plus(other: DateTimePeriod): DateTimePeriod =
     safeAdd(totalNanoseconds, other.totalNanoseconds),
 )
 
+/**
+ * Subtracts one [DateTimePeriod] instance from another.
+ *
+ * @throws DateTimeArithmeticException if arithmetic overflow happens.
+ */
+public operator fun DateTimePeriod.minus(other: DateTimePeriod) : DateTimePeriod = buildDateTimePeriod(
+    safeAdd(totalMonths, -other.totalMonths),
+    safeAdd(days, -other.days),
+    safeAdd(totalNanoseconds, -other.totalNanoseconds)
+)
+
 /**
  * Adds two [DatePeriod] instances.
  *
@@ -457,3 +468,13 @@ public operator fun DatePeriod.plus(other: DatePeriod): DatePeriod = DatePeriod(
     safeAdd(totalMonths, other.totalMonths),
     safeAdd(days, other.days),
 )
+
+/**
+ * Subtracts one [DatePeriod] instance from another.
+ *
+ * @throws DateTimeArithmeticException if arithmetic overflow happens.
+ */
+public operator fun DatePeriod.minus(other: DatePeriod): DatePeriod = DatePeriod(
+    safeAdd(totalMonths, -other.totalMonths),
+    safeAdd(days, -other.days)
+)