Enable Java 8 language feature support

app/build.gradle

@@ -91,6 +91,14 @@ android {
         checkReleaseBuilds false
     }
 
+    compileOptions {
+        sourceCompatibility = 1.8
+        targetCompatibility = 1.8
+    }
+
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
 }
 
 dependencies {