fix: use System.nanoTime() for cron check-in duration measurement

System.currentTimeMillis() is a wall-clock value and is subject to
NTP adjustments and DST transitions. For long-running cron jobs this
can produce incorrect or even negative durations in the check-in payload.

Switch the start/end capture in CheckInUtils.withCheckIn() and the three
SentryCheckInAdvice implementations (sentry-spring, sentry-spring-jakarta,
sentry-spring-7) to System.nanoTime(), which is guaranteed monotonic.
Use DateUtils.nanosToSeconds() (already present) to convert the delta.

Fixes #5579

Author: tsushanth

sentry-spring-7/src/main/java/io/sentry/spring7/checkin/SentryCheckInAdvice.java

@@ -91,7 +91,7 @@ public Object invoke(final @NotNull MethodInvocation invocation) throws Throwabl
       TracingUtils.startNewTrace(scopes);
 
       @Nullable SentryId checkInId = null;
-      final long startTime = System.currentTimeMillis();
+      final long startTime = System.nanoTime();
       boolean didError = false;
 
       try {
@@ -105,7 +105,7 @@ public Object invoke(final @NotNull MethodInvocation invocation) throws Throwabl
       } finally {
         final @NotNull CheckInStatus status = didError ? CheckInStatus.ERROR : CheckInStatus.OK;
         CheckIn checkIn = new CheckIn(checkInId, monitorSlug, status);
-        checkIn.setDuration(DateUtils.millisToSeconds(System.currentTimeMillis() - startTime));
+        checkIn.setDuration(DateUtils.nanosToSeconds(System.nanoTime() - startTime));
         scopes.captureCheckIn(checkIn);
       }
     }

sentry-spring-jakarta/src/main/java/io/sentry/spring/jakarta/checkin/SentryCheckInAdvice.java

@@ -91,7 +91,7 @@ public Object invoke(final @NotNull MethodInvocation invocation) throws Throwabl
       TracingUtils.startNewTrace(scopes);
 
       @Nullable SentryId checkInId = null;
-      final long startTime = System.currentTimeMillis();
+      final long startTime = System.nanoTime();
       boolean didError = false;
 
       try {
@@ -105,7 +105,7 @@ public Object invoke(final @NotNull MethodInvocation invocation) throws Throwabl
       } finally {
         final @NotNull CheckInStatus status = didError ? CheckInStatus.ERROR : CheckInStatus.OK;
         CheckIn checkIn = new CheckIn(checkInId, monitorSlug, status);
-        checkIn.setDuration(DateUtils.millisToSeconds(System.currentTimeMillis() - startTime));
+        checkIn.setDuration(DateUtils.nanosToSeconds(System.nanoTime() - startTime));
         scopes.captureCheckIn(checkIn);
       }
     }

sentry-spring/src/main/java/io/sentry/spring/checkin/SentryCheckInAdvice.java

@@ -94,7 +94,7 @@ public Object invoke(final @NotNull MethodInvocation invocation) throws Throwabl
       TracingUtils.startNewTrace(scopes);
 
       @Nullable SentryId checkInId = null;
-      final long startTime = System.currentTimeMillis();
+      final long startTime = System.nanoTime();
       boolean didError = false;
 
       try {
@@ -108,7 +108,7 @@ public Object invoke(final @NotNull MethodInvocation invocation) throws Throwabl
       } finally {
         final @NotNull CheckInStatus status = didError ? CheckInStatus.ERROR : CheckInStatus.OK;
         CheckIn checkIn = new CheckIn(checkInId, monitorSlug, status);
-        checkIn.setDuration(DateUtils.millisToSeconds(System.currentTimeMillis() - startTime));
+        checkIn.setDuration(DateUtils.nanosToSeconds(System.nanoTime() - startTime));
         scopes.captureCheckIn(checkIn);
       }
     }

sentry/src/main/java/io/sentry/util/CheckInUtils.java

@@ -37,7 +37,7 @@ public static <U> U withCheckIn(
     try (final @NotNull ISentryLifecycleToken ignored =
             Sentry.forkedScopes("CheckInUtils").makeCurrent()) {
       final @NotNull IScopes scopes = Sentry.getCurrentScopes();
-      final long startTime = System.currentTimeMillis();
+      final long startTime = System.nanoTime();
       boolean didError = false;
 
       TracingUtils.startNewTrace(scopes);
@@ -61,7 +61,7 @@ public static <U> U withCheckIn(
         if (environment != null) {
           checkIn.setEnvironment(environment);
         }
-        checkIn.setDuration(DateUtils.millisToSeconds(System.currentTimeMillis() - startTime));
+        checkIn.setDuration(DateUtils.nanosToSeconds(System.nanoTime() - startTime));
         scopes.captureCheckIn(checkIn);
       }
     }