feat(investment): broken-period interest as an expense in the interest schedule

RBI UCB Investment Directions 2025, para 152: broken-period interest paid
to the seller on G-Sec / approved securities is not part of cost but an
expense (confirmed by Jitendra Sir; GL 500606). The interest schedule
therefore no longer carries it as a receivable to be cleared by the first
coupon: the first coupon is income in full. Tests updated.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

fineract-provider/src/test/java/org/apache/fineract/portfolio/investment/service/InvestmentInterestCalculatorTest.java

@@ -100,15 +100,15 @@ class InvestmentInterestCalculatorTest {
     }
 
     @Test
-    void scheduleClearsPurchasedInterestAndProvisionsAtEachClosing() {
-        final List<ScheduleRow> rows = InvestmentInterestCalculator.schedule(ONE_CRORE, RATE, MATURITY, LAST_COUPON, DEAL,
-                new BigDecimal("120833"));
+    void scheduleProvisionsAtEachClosingAndClearsAtTheCoupon() {
+        final List<ScheduleRow> rows = InvestmentInterestCalculator.schedule(ONE_CRORE, RATE, MATURITY, LAST_COUPON, DEAL);
 
         // 16 coupons + 15 closings (Mar 2027 … Mar 2034); 30-09-2026 is before the deal, so it is the seller's.
         assertEquals(31, rows.size());
 
-        // First coupon: 1,20,833 paid to the seller is recovered, only the rest is our income.
-        assertRow(rows.get(0), TYPE_COUPON, LocalDate.of(2027, 2, 10), LocalDate.of(2026, 8, 11), 180, "375000", "120833", "254167");
+        // First coupon is income in full: the 1,20,833 paid to the seller was booked as an expense at purchase (RBI
+        // para 152).
+        assertRow(rows.get(0), TYPE_COUPON, LocalDate.of(2027, 2, 10), LocalDate.of(2026, 8, 11), 180, "375000", "0", "375000");
         // 31 March closing: 50 days earned since 10 Feb, nothing booked yet.
         assertRow(rows.get(1), TYPE_PROVISION, LocalDate.of(2027, 3, 31), LocalDate.of(2027, 2, 11), 50, "104167", "0", "104167");
         // August coupon clears the March provision.
@@ -119,25 +119,25 @@ class InvestmentInterestCalculatorTest {
         assertEquals(TYPE_COUPON, last.type());
         assertEquals(MATURITY, last.date());
 
-        // Over the life, income booked = all coupons − interest bought from the seller.
+        // Over the life, income booked = all the coupons.
         final BigDecimal totalIncome = rows.stream().map(ScheduleRow::amount).reduce(BigDecimal.ZERO, BigDecimal::add);
-        assertEquals(new BigDecimal("375000").multiply(BigDecimal.valueOf(16)).subtract(new BigDecimal("120833")), totalIncome);
+        assertEquals(new BigDecimal("375000").multiply(BigDecimal.valueOf(16)), totalIncome);
     }
 
     @Test
     void closingOnACouponDateIsNotProvisionedTwice() {
         // Coupons on 31 Mar / 30 Sep: every closing is a coupon day, so there are no provision lines.
         final List<ScheduleRow> rows = InvestmentInterestCalculator.schedule(ONE_CRORE, RATE, LocalDate.of(2028, 3, 31),
-                LocalDate.of(2026, 9, 30), DEAL, BigDecimal.ZERO);
+                LocalDate.of(2026, 9, 30), DEAL);
         assertEquals(3, rows.size());
         assertTrue(rows.stream().allMatch(r -> TYPE_COUPON.equals(r.type())));
     }
 
     @Test
     void scheduleIsEmptyWithoutRateOrDates() {
-        assertTrue(InvestmentInterestCalculator.schedule(ONE_CRORE, BigDecimal.ZERO, MATURITY, LAST_COUPON, DEAL, null).isEmpty());
-        assertTrue(InvestmentInterestCalculator.schedule(ONE_CRORE, RATE, null, LAST_COUPON, DEAL, null).isEmpty());
-        assertTrue(InvestmentInterestCalculator.schedule(ONE_CRORE, RATE, MATURITY, null, DEAL, null).isEmpty());
+        assertTrue(InvestmentInterestCalculator.schedule(ONE_CRORE, BigDecimal.ZERO, MATURITY, LAST_COUPON, DEAL).isEmpty());
+        assertTrue(InvestmentInterestCalculator.schedule(ONE_CRORE, RATE, null, LAST_COUPON, DEAL).isEmpty());
+        assertTrue(InvestmentInterestCalculator.schedule(ONE_CRORE, RATE, MATURITY, null, DEAL).isEmpty());
     }
 
     @Test