Merge pull request #115 from weiminyu/disable_werror

Allow switching off the -Werror javac option

java_common.gradle

@@ -15,6 +15,12 @@ dependencies {
 }
 
 tasks.withType(JavaCompile).configureEach {
+    // The -Werror flag causes Intellij to fail on deprecated api use.
+    // Allow IDE user to turn off this flag by specifying a Gradle VM
+    // option from inside the IDE.
+    if (System.getProperty('no_werror') != 'true') {
+        options.compilerArgs << "-Werror"
+    }
     options.compilerArgs << "-Werror"
     options.errorprone.disableWarningsInGeneratedCode = true
     options.errorprone.errorproneArgumentProviders.add([