Use Gradle Plugin to generate proto files automatically

.gitignore

@@ -48,9 +48,6 @@ gradle.properties
 **/secrets
 *.json
 
-# Generated java classes from proto files
-src/main/java/
-
 # Temporary Git Files
 **/*.orig
 

README.adoc

@@ -56,6 +56,12 @@ However, the pre-compiled `JARs` are also published to the link:https://github.c
 - how to use with link:https://github.com/protocolbuffers/protobuf/tree/master/java#gradle[Gradle]
 - how to use with link:https://github.com/protocolbuffers/protobuf/tree/master/java#use-java-protocol-buffers-on-android[Android]
 
+    Instead of using the pre-compiled `java` classes (published `JAR`s) it's recommended to use `javalite` for Android. These classes can either be manually generated with:
+
+    protoc --java_out=lite:./src/main/java/ src/main/protos/de/cyface/protos/model/measurement.proto
+
+Or you can download the `proto` link:protoc --java_out=./src/main/java/ src/main/protos/de/cyface/protos/model/measurement.proto[files] from this repository and then generate the classes using the link:https://github.com/google/protobuf-gradle-plugin[Gradle Plugin]. This is done in the link:https://github.com/cyface-de/android-backend[Cyface Android SDK] - check it out if you need an example.
+
 The serializers encode the data in an efficient way, the decision process is documented link:https://cyface.atlassian.net/wiki/spaces/IM/pages/1535148033/Datenformat+bertragungsprotokoll+2021[internally].
 
 

build.gradle

@@ -35,6 +35,7 @@ plugins {
   id 'maven-publish'
   //noinspection SpellCheckingInspection
   id 'com.github.johnrengelman.shadow' version '6.1.0'
+  id 'com.google.protobuf' version '0.8.16'
 }
 
 group = 'de.cyface'
@@ -69,7 +70,7 @@ repositories {
 
 // Code Quality Checker
 dependencies {
-  // Protobuf generated java files
+  // Generate java files from the Protobuf files
   implementation "com.google.protobuf:protobuf-java:$protobufVersion"
 
   // Utility
@@ -85,6 +86,21 @@ dependencies {
   testRuntimeOnly "org.junit.jupiter:junit-jupiter-engine"
 }
 
+// See https://github.com/google/protobuf-gradle-plugin
+protobuf {
+  protoc {
+    artifact = "com.google.protobuf:protoc:$protobufVersion"
+  }
+  generateProtoTasks {
+    //noinspection GroovyAssignabilityCheck
+    all().each { task ->
+      task.builtins {
+        java {}
+      }
+    }
+  }
+}
+
 test {
   useJUnitPlatform()
   testLogging {
@@ -113,7 +129,7 @@ publishing {
   publications {
     //noinspection GroovyAssignabilityCheck
     publishExecutable(MavenPublication) {
-      //noinspection GroovyAssignabilityCheckssssssss
+      //noinspection GroovyAssignabilityCheck
       from components.java
     }
   }