Last attempt at toNanosPart

Author: cquiroz

core/shared/src/main/scala/org/threeten/bp/Duration.scala

@@ -1215,6 +1215,21 @@ final class Duration private (private val seconds: Long, private val nanos: Int)
     Math.addExact(result, nanos.toLong)
   }
 
+  /**
+   * Get the nanoseconds part within seconds of the duration.
+   *
+   * The length of the duration is stored using two fields - seconds and nanoseconds. The
+   * nanoseconds part is a value from 0 to 999,999,999 that is an adjustment to the length in
+   * seconds. The total duration is defined by calling getNano() and getSeconds().
+   *
+   * This instance is immutable and unaffected by this method call.
+   *
+   * @return
+   *   the nanoseconds within the second part of the length of the duration, from 0 to 999,999,999
+   * @since 9
+   */
+  def toNanosPart: Int = nanos
+
   /**
    * Compares this duration to the specified {@code Duration}.
    *

tests/shared/src/test/scala/org/threeten/bp/TestDuration.scala

@@ -1902,14 +1902,15 @@ class TestDuration extends AnyFunSuite with AssertionsHelper {
     assertEquals(Duration.ofDays(387).plusHours(18).plusMinutes(29).plusSeconds(88).plusMillis(234).toHoursPart, 18)
     assertEquals(Duration.ofDays(387).plusHours(18).plusMinutes(29).plusSeconds(38).plusMillis(234).toMinutesPart, 29)
     assertEquals(Duration.ofDays(387).plusHours(18).plusMinutes(29).plusSeconds(88).plusMillis(234).toSecondsPart, 28)
-    assertEquals(Duration.ofDays(387).plusHours(18).plusMinutes(29).plusSeconds(88).plusMillis(234).toMillisPart, 234)
+    assertEquals(Duration.ofDays(387).plusHours(18).plusMinutes(29).plusSeconds(88).plusMillis(234).plusNanos(4000).toNanosPart, 234004000)
   }
 
   test("test_*_part_with_overflow") {
     assertEquals(Duration.ofDays(3).plusHours(38).toDaysPart, 4)
     assertEquals(Duration.ofDays(0).plusHours(18).plusMinutes(79).toHoursPart, 19)
     assertEquals(Duration.ofDays(0).plusHours(18).plusMinutes(19).plusSeconds(90).toSecondsPart, 30)
     assertEquals(Duration.ofDays(0).plusHours(18).plusMinutes(19).plusSeconds(90).plusMillis(10000).toSecondsPart, 40)
+    assertEquals(Duration.ofDays(0).plusHours(18).plusMinutes(19).plusSeconds(90).plusMillis(10000).plusNanos(666666).toNanosPart, 666666)
   }
 
   test("test_negated_overflow") {
@@ -1938,11 +1939,13 @@ class TestDuration extends AnyFunSuite with AssertionsHelper {
   test("test_toNanos") {
     val test: Duration = Duration.ofSeconds(321, 123456789)
     assertEquals(test.toNanos, 321123456789L)
+    assertEquals(test.toNanosPart, 123456789L)
   }
 
   test("test_toNanos_max") {
     val test: Duration = Duration.ofSeconds(0, Long.MaxValue)
     assertEquals(test.toNanos, Long.MaxValue)
+    assertEquals(test.toNanosPart, 854775807L)
   }
 
   test("test_toNanos_tooBig") {