From 353310a47b4dc3ac09a16b98112b68d1790ee803 Mon Sep 17 00:00:00 2001
From: Jukka Oikarinen <jukka.oikarinen@polar.com>
Date: Tue, 10 Aug 2021 12:03:29 +0300
Subject: [PATCH] Fix #179: App crashed because of using function
 HashMap#putIfAbsent which only available from Android API 24 onwards

---
 .../androidcommunications/api/ble/model/gatt/BleGattBase.java | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sources/Android/android-communications/library/src/main/java/com/polar/androidcommunications/api/ble/model/gatt/BleGattBase.java b/sources/Android/android-communications/library/src/main/java/com/polar/androidcommunications/api/ble/model/gatt/BleGattBase.java
index b7b60991..2d7ae0a4 100755
--- a/sources/Android/android-communications/library/src/main/java/com/polar/androidcommunications/api/ble/model/gatt/BleGattBase.java
+++ b/sources/Android/android-communications/library/src/main/java/com/polar/androidcommunications/api/ble/model/gatt/BleGattBase.java
@@ -303,7 +303,9 @@ protected void addCharacteristic(final UUID characteristic, int properties) {
         if ((properties & PROPERTY_READ) != 0 && !containsCharacteristicRead(characteristic)) {
             characteristicsRead.put(characteristic, true);
         }
-        characteristics.putIfAbsent(characteristic, true);
+        if (!characteristics.containsKey(characteristic)) {
+            characteristics.put(characteristic, true);
+        }
     }
 
     protected void addAvailableCharacteristic(UUID chr, int property) {