From 7d6ef259b3f578ef4d17c3f554c00aad65e21408 Mon Sep 17 00:00:00 2001
From: Sebastien Houver <shouver@pictet-technologies.com>
Date: Thu, 8 Oct 2020 12:09:17 +0200
Subject: [PATCH] adding support for experimental_allow_proto3_optional cf.
 https://github.com/xolstice/protobuf-maven-plugin/issues/77

---
 .../plugin/protobuf/AbstractProtocMojo.java   | 14 +++++++++++
 .../maven/plugin/protobuf/Protoc.java         | 24 +++++++++++++++++--
 2 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/src/main/java/org/xolstice/maven/plugin/protobuf/AbstractProtocMojo.java b/src/main/java/org/xolstice/maven/plugin/protobuf/AbstractProtocMojo.java
index 9b993dc6..55e7b474 100644
--- a/src/main/java/org/xolstice/maven/plugin/protobuf/AbstractProtocMojo.java
+++ b/src/main/java/org/xolstice/maven/plugin/protobuf/AbstractProtocMojo.java
@@ -312,6 +312,19 @@ abstract class AbstractProtocMojo extends AbstractMojo {
     )
     protected boolean useArgumentFile;
 
+    /**
+     * If set to {@code true}, experimental optional feature will be enabled.
+     *
+     * <p><b>NOTE:</b> This is only supported for protoc 3.12.0 and higher.</p>
+     *
+     * @since 0.7.0
+     */
+    @Parameter(
+            required = false,
+            defaultValue = "false"
+    )
+    protected boolean useExperimentalOptional;
+
     /**
      * Specifies one of more custom protoc plugins, written in Java
      * and available as Maven artifacts. An executable plugin will be created
@@ -623,6 +636,7 @@ protected void addProtocBuilderParameters(final Protoc.Builder protocBuilder) {
         }
         protocBuilder.setTempDirectory(tempDirectory);
         protocBuilder.useArgumentFile(useArgumentFile);
+        protocBuilder.useExperimentalOptional(useExperimentalOptional);
     }
 
     /**
diff --git a/src/main/java/org/xolstice/maven/plugin/protobuf/Protoc.java b/src/main/java/org/xolstice/maven/plugin/protobuf/Protoc.java
index d8097636..6800b3ab 100644
--- a/src/main/java/org/xolstice/maven/plugin/protobuf/Protoc.java
+++ b/src/main/java/org/xolstice/maven/plugin/protobuf/Protoc.java
@@ -124,6 +124,11 @@ final class Protoc {
      */
     private final boolean useArgumentFile;
 
+    /**
+     * A boolean indicating if experimental optional feature should be enabled.
+     */
+    private boolean useExperimentalOptional;
+
     /**
      * Constructs a new instance. This should only be used by the {@link Builder}.
      *
@@ -148,6 +153,7 @@ final class Protoc {
      * @param nativePluginParameter an optional parameter for a native plugin.
      * @param tempDirectory a directory where temporary files will be generated.
      * @param useArgumentFile If {@code true}, parameters to protoc will be put in an argument file
+     * @param useExperimentalOptional If {@code true}, experimental optional feature will be enabled
      */
     private Protoc(
             final String executable,
@@ -168,7 +174,8 @@ private Protoc(
             final String nativePluginExecutable,
             final String nativePluginParameter,
             final File tempDirectory,
-            final boolean useArgumentFile
+            final boolean useArgumentFile,
+            final boolean useExperimentalOptional
     ) {
         if (executable == null) {
             throw new MojoConfigurationException("'executable' is null");
@@ -198,6 +205,7 @@ private Protoc(
         this.nativePluginParameter = nativePluginParameter;
         this.tempDirectory = tempDirectory;
         this.useArgumentFile = useArgumentFile;
+        this.useExperimentalOptional = useExperimentalOptional;
         this.error = new StringStreamConsumer();
         this.output = new StringStreamConsumer();
     }
@@ -255,6 +263,10 @@ public List<String> buildProtocCommand() {
         for (final File protoPathElement : protoPathElements) {
             command.add("--proto_path=" + protoPathElement);
         }
+        if (useExperimentalOptional) {
+            command.add("--experimental_allow_proto3_optional");
+
+        }
         if (javaOutputDirectory != null) {
             String outputOption = "--java_out=";
             if (nativePluginParameter != null) {
@@ -506,6 +518,8 @@ static final class Builder {
 
         private boolean useArgumentFile;
 
+        private boolean useExperimentalOptional;
+
         /**
          * Constructs a new builder.
          *
@@ -749,6 +763,11 @@ public Builder useArgumentFile(final boolean useArgumentFile) {
             return this;
         }
 
+        public Builder useExperimentalOptional(final boolean useExperimentalOptional) {
+            this.useExperimentalOptional = useExperimentalOptional;
+            return this;
+        }
+
         private void checkProtoFileIsInProtopath(final File protoFile) {
             if (!protoFile.isFile()) {
                 throw new MojoConfigurationException("Not a regular file: " + protoFile.getAbsolutePath());
@@ -862,7 +881,8 @@ public Protoc build() {
                     nativePluginExecutable,
                     nativePluginParameter,
                     tempDirectory,
-                    useArgumentFile);
+                    useArgumentFile,
+                    useExperimentalOptional);
         }
     }
 }