Deprecate duplicated JSON serialization for Dependency

Author: Geod24

source/dub/dependency.d

@@ -249,19 +249,23 @@ struct Dependency {
 		string (`versionSpec`), while more complex specifications will be
 		represented as a JSON object with optional "version", "path", "optional"
 		and "default" fields.
+
+		Params:
+		  selections = We are serializing `dub.selections.json`, don't write out
+			  `optional` and `default`.
 	*/
-	Json toJson()
+	Json toJson(bool selections = false)
 	const @trusted { // NOTE Path and Json is @system in vibe.d 0.7.x and in the compatibility layer
 		Json json;
-		if( path.empty && repository.empty && !optional ){
+		if (path.empty && repository.empty && (!optional || selections)) {
 			json = Json(this.versionSpec);
 		} else {
 			json = Json.emptyObject;
 			json["version"] = this.versionSpec;
 			if (!path.empty) json["path"] = path.toString();
 			if (!repository.empty) json["repository"] = repository.toString;
-			if (optional) json["optional"] = true;
-			if (default_) json["default"] = true;
+			if (!selections && optional) json["optional"] = true;
+			if (!selections && default_) json["default"] = true;
 		}
 		return json;
 	}

source/dub/project.d

@@ -1843,15 +1843,10 @@ final class SelectedVersions {
 		m_bare = false;
 	}
 
+	deprecated("Use `dub.dependency : Dependency.toJson(true)`")
 	static Json dependencyToJson(Dependency d)
 	{
-		if (!d.repository.empty) {
-			return serializeToJson([
-				"version": d.version_.toString(),
-				"repository": d.repository.toString,
-			]);
-		} else if (d.path.empty) return Json(d.version_.toString());
-		else return serializeToJson(["path": d.path.toString()]);
+		return d.toJson(true);
 	}
 
 	static Dependency dependencyFromJson(Json j)
@@ -1873,7 +1868,7 @@ final class SelectedVersions {
 		serialized["fileVersion"] = m_selections.fileVersion;
 		serialized["versions"] = Json.emptyObject;
 		foreach (p, dep; m_selections.versions)
-			serialized["versions"][p] = dependencyToJson(dep);
+			serialized["versions"][p] = dep.toJson(true);
 		return serialized;
 	}