Merge remote-tracking branch 'origin/master'

.travis.yml

 language: android
-#### use android since there are android components####
-jdk:
-  - openjdk11
-os: linux
+sudo: required
+jdk: oraclejdk8
 
+env:
+  global:
+    - ANDROID_API_LEVEL=28
+    - ANDROID_BUILD_TOOLS_VERSION=28.0.3
+    - ANDROID_ABI=armeabi-v7a
 
 android:
   components:
-    - build-tools-29
-    - android-29
-    - extra
+    - tools
+    - platform-tools
+    - tools
+    - extra-android-m2repository
   licenses:
+    - 'android-sdk-preview-license-52d11cd2'
     - 'android-sdk-license-.+'
     - 'google-gdk-license-.+'
-    - 'android-sdk-preview-license-.+'
 
+before_install:
+  - touch $HOME/.android/repositories.cfg
+  - yes | sdkmanager "platforms;android-28"
+  - yes | sdkmanager "build-tools;28.0.3"
 
+before_cache:
+  - rm -f  $HOME/.gradle/caches/modules-2/modules-2.lock
+  - rm -fr $HOME/.gradle/caches/*/plugin-resolution/
 
-install: true
-
+cache:
+  directories:
+    - $HOME/.gradle/caches/
+    - $HOME/.gradle/wrapper/
+    - $HOME/.android/build-cache
 
 before_script:
   - chmod +x gradlew
 
 script:
-  - ./gradlew clean build -i --continue
-
+  - ./gradlew clean build
+  - ./gradlew test
\ No newline at end of file