From 4c644de1e8d485c3da1e07149d5b7c1931f4de6c Mon Sep 17 00:00:00 2001
From: hluhovskyi <hluhovskyi@gmail.com>
Date: Thu, 4 Jul 2019 16:17:46 +0300
Subject: [PATCH] Fix NPE when debouncing empty source

---
 .../internal/operators/flowable/FlowableDebounce.java  |  4 +++-
 .../operators/observable/ObservableDebounce.java       |  4 +++-
 .../operators/flowable/FlowableDebounceTest.java       | 10 ++++++++++
 .../operators/observable/ObservableDebounceTest.java   | 10 ++++++++++
 4 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/src/main/java/io/reactivex/internal/operators/flowable/FlowableDebounce.java b/src/main/java/io/reactivex/internal/operators/flowable/FlowableDebounce.java
index 92b1c48254..143e61ec55 100644
--- a/src/main/java/io/reactivex/internal/operators/flowable/FlowableDebounce.java
+++ b/src/main/java/io/reactivex/internal/operators/flowable/FlowableDebounce.java
@@ -119,7 +119,9 @@ public void onComplete() {
             if (!DisposableHelper.isDisposed(d)) {
                 @SuppressWarnings("unchecked")
                 DebounceInnerSubscriber<T, U> dis = (DebounceInnerSubscriber<T, U>)d;
-                dis.emit();
+                if (dis != null) {
+                    dis.emit();
+                }
                 DisposableHelper.dispose(debouncer);
                 downstream.onComplete();
             }
diff --git a/src/main/java/io/reactivex/internal/operators/observable/ObservableDebounce.java b/src/main/java/io/reactivex/internal/operators/observable/ObservableDebounce.java
index 2c056eb70e..db8b9d4794 100644
--- a/src/main/java/io/reactivex/internal/operators/observable/ObservableDebounce.java
+++ b/src/main/java/io/reactivex/internal/operators/observable/ObservableDebounce.java
@@ -112,7 +112,9 @@ public void onComplete() {
             if (d != DisposableHelper.DISPOSED) {
                 @SuppressWarnings("unchecked")
                 DebounceInnerObserver<T, U> dis = (DebounceInnerObserver<T, U>)d;
-                dis.emit();
+                if (dis != null) {
+                    dis.emit();
+                }
                 DisposableHelper.dispose(debouncer);
                 downstream.onComplete();
             }
diff --git a/src/test/java/io/reactivex/internal/operators/flowable/FlowableDebounceTest.java b/src/test/java/io/reactivex/internal/operators/flowable/FlowableDebounceTest.java
index 651b1946d5..bcde987665 100644
--- a/src/test/java/io/reactivex/internal/operators/flowable/FlowableDebounceTest.java
+++ b/src/test/java/io/reactivex/internal/operators/flowable/FlowableDebounceTest.java
@@ -547,4 +547,14 @@ public void timedError() {
         .test()
         .assertFailure(TestException.class);
     }
+
+    @Test
+    public void debounceOnEmpty() {
+        Flowable.empty().debounce(new Function<Object, Publisher<Object>>() {
+            @Override
+            public Publisher<Object> apply(Object o) {
+                return Flowable.just(new Object());
+            }
+        }).subscribe();
+    }
 }
diff --git a/src/test/java/io/reactivex/internal/operators/observable/ObservableDebounceTest.java b/src/test/java/io/reactivex/internal/operators/observable/ObservableDebounceTest.java
index 53a19b08e9..b8ada4e3be 100644
--- a/src/test/java/io/reactivex/internal/operators/observable/ObservableDebounceTest.java
+++ b/src/test/java/io/reactivex/internal/operators/observable/ObservableDebounceTest.java
@@ -506,4 +506,14 @@ public void timedError() {
         .test()
         .assertFailure(TestException.class);
     }
+
+    @Test
+    public void debounceOnEmpty() {
+        Observable.empty().debounce(new Function<Object, ObservableSource<Object>>() {
+            @Override
+            public ObservableSource<Object> apply(Object o) {
+                return Observable.just(new Object());
+            }
+        }).subscribe();
+    }
 }