Create multiproject build, add python grpc build support

protobuf/build.gradle

@@ -0,0 +1,48 @@
+plugins {
+    id 'java'
+    id 'com.google.protobuf'
+    id 'idea'
+}
+
+configurations {
+
+    // For grpc python codegen.
+    python {
+        canBeResolved = false
+        canBeConsumed = true
+    }
+}
+
+protobuf {
+    protoc { artifact = 'com.google.protobuf:protoc:3.11.0' }
+    plugins {
+        grpc {
+            artifact = 'io.grpc:protoc-gen-grpc-java:1.28.1' // CURRENT_GRPC_VERSION
+        }
+        grpc_python { path = "$projectDir/grpc_python_plugin" }
+    }
+    generateProtoTasks {
+        all().each { task ->
+            task.builtins {
+                java { option 'lite' }
+
+                python {}
+            }
+            task.plugins {
+                grpc { // Options added to --grpc_out
+                    option 'lite'
+                }
+                grpc_python {
+                    outputSubDir = 'python'
+                }
+            }
+        }
+    }
+}
+
+dependencies {
+    implementation 'io.grpc:grpc-okhttp:1.28.1' // CURRENT_GRPC_VERSION
+    implementation 'io.grpc:grpc-protobuf-lite:1.28.1' // CURRENT_GRPC_VERSION
+    implementation 'io.grpc:grpc-stub:1.28.1' // CURRENT_GRPC_VERSION
+    implementation 'javax.annotation:javax.annotation-api:1.2'
+}