Configure Android Studio to pickup protobuf generated sources

libsignal/service/build.gradle

@@ -14,6 +14,7 @@ apply plugin: 'com.google.protobuf'
 apply plugin: 'maven'
 apply plugin: 'signing'
 apply plugin: 'witness'
+apply plugin: 'idea'
 apply from: 'witness-verifications.gradle'
 
 sourceCompatibility = 1.7
@@ -67,6 +68,12 @@ protobuf {
     }
 }
 
+idea {
+    module {
+        generatedSourceDirs += file("${protobuf.generatedFilesBaseDir}/main/java")
+    }
+}
+
 def isReleaseBuild() {
     return version.contains("SNAPSHOT") == false
 }