DBZ-7436 Add empty statistics for SingleDuration to avoid NPE

(cherry picked from commit fa338b6)

debezium-core/src/main/java/io/debezium/util/Stopwatch.java

@@ -496,6 +496,11 @@ public String toString() {
     private static final class SingleDuration extends BaseDurations {
         private final AtomicReference<Statistics> stats = new AtomicReference<>();
 
+        SingleDuration() {
+            LongSummaryStatistics stats = new LongSummaryStatistics();
+            this.stats.set(createStatistics(stats));
+        }
+
         @Override
         public Statistics statistics() {
             return stats.get();

debezium-core/src/test/java/io/debezium/util/StopwatchTest.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright Debezium Authors.
+ *
+ * Licensed under the Apache Software License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
+ */
+package io.debezium.util;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Test;
+
+import io.debezium.doc.FixFor;
+
+public class StopwatchTest {
+
+    @FixFor("DBZ-7436")
+    @Test
+    public void whenCallingDurationsOnAStartedStopwatchItShouldNotFailWithANPE() {
+
+        Stopwatch reusable = Stopwatch.reusable();
+
+        reusable.start();
+
+        String reusableStopWatchResults = reusable.durations().toString();
+
+        Stopwatch.StopwatchSet multiple = Stopwatch.multiple();
+
+        Stopwatch stopwatch = multiple.create();
+
+        String multipleStopWatchResults = stopwatch.durations().toString();
+
+        Stopwatch accumulating = Stopwatch.accumulating();
+
+        String accumulatingStopWatchResults = accumulating.durations().toString();
+
+        assertThat(reusableStopWatchResults).isEqualTo("  0.00000s total;   0 samples;  0.00000s avg;  0.00000s min;  0.00000s max");
+        assertThat(multipleStopWatchResults).isEqualTo("  0.00000s total;   0 samples;  0.00000s avg;  0.00000s min;  0.00000s max");
+        assertThat(accumulatingStopWatchResults).isEqualTo("  0.00000s total;   0 samples;  0.00000s avg;  0.00000s min;  0.00000s max");
+    }
+}