🆕 #1392 增加weixin-graal模块，配合graal以产生native-image配置。

目的：解决native-image中gson功能无效的问题。

可以通过项目的 native-image Profile 来启用:
mvn -P native-image -Dmaven.test.skip=true clean source:jar install

编译时会在各包中增加2个文件：
META-INF/native-image/.../reflection-config.json
META-INF/native-image/.../native-image.properties

weixin-java-open/pom.xml

@@ -107,5 +107,35 @@
     </plugins>
   </build>
 
+  <profiles>
+    <profile>
+      <id>native-image</id>
+      <activation>
+        <activeByDefault>false</activeByDefault>
+      </activation>
+
+      <build>
+        <plugins>
+          <plugin>
+            <groupId>org.apache.maven.plugins</groupId>
+            <artifactId>maven-compiler-plugin</artifactId>
+            <version>3.5.1</version>
+            <configuration>
+              <annotationProcessors>
+                cn.binarywang.wx.graal.GraalProcessor,lombok.launch.AnnotationProcessorHider$AnnotationProcessor,lombok.launch.AnnotationProcessorHider$ClaimingProcessor
+              </annotationProcessors>
+              <annotationProcessorPaths>
+                <path>
+                  <groupId>com.github.binarywang</groupId>
+                  <artifactId>weixin-graal</artifactId>
+                  <version>${project.version}</version>
+                </path>
+              </annotationProcessorPaths>
+            </configuration>
+          </plugin>
+        </plugins>
+      </build>
+    </profile>
+  </profiles>
 
 </project>