Android : added review comments point

Author: Sangamesh1997

build.gradle

@@ -34,6 +34,15 @@ subprojects {
         }
     }
 
+    tasks.withType(JavaCompile).configureEach {
+        it.options.compilerArgs += [
+                "-Xlint:all"
+        ]
+        if (rootProject.hasProperty('failOnWarnings') && rootProject.failOnWarnings.toBoolean()) {
+            it.options.compilerArgs += ["-Werror"]
+        }
+    }
+
     repositories {
         maven { // The google mirror is less flaky than mavenCentral()
             url "https://maven-central.storage-download.googleapis.com/maven2/"