chore(java-sdk): compile example modules into source jar (#336)

Author: seeflood

sdk/java-sdk/README-zh.md

@@ -75,9 +75,9 @@ mvn clean install
 
 #### 第三步：运行java sdk示例
 通过以下Examples示例来了解如何使用SDK:
-* [Hello world](./examples/src/main/java/io/mosn/layotto/examples/helloworld)
-* [State management](./examples/src/main/java/io/mosn/layotto/examples/state)
-* [Pubsub API](./examples/src/main/java/io/mosn/layotto/examples/pubsub)
+* [Hello world](./examples/src/test/java/io/mosn/layotto/examples/helloworld)
+* [State management](./examples/src/test/java/io/mosn/layotto/examples/state)
+* [Pubsub API](./examples/src/test/java/io/mosn/layotto/examples/pubsub)
 
 ## java sdk开发指南
 ### java sdk职责

sdk/java-sdk/README.md

@@ -46,9 +46,9 @@ mvn clean install
 
 
 Try the following examples to learn more about this SDK:
-* [Hello world](./examples/src/main/java/io/mosn/layotto/examples/helloworld)
-* [State management](./examples/src/main/java/io/mosn/layotto/examples/state)
-* [Pubsub API](./examples/src/main/java/io/mosn/layotto/examples/pubsub)
+* [Hello world](./examples/src/test/java/io/mosn/layotto/examples/helloworld)
+* [State management](./examples/src/test/java/io/mosn/layotto/examples/state)
+* [Pubsub API](./examples/src/test/java/io/mosn/layotto/examples/pubsub)
 
 ## java sdk developer guide 
 ### How to format java sdk code

sdk/java-sdk/examples/pom.xml

@@ -12,13 +12,6 @@
 
     <artifactId>examples</artifactId>
 
-
-    <properties>
-        <!-- Build args -->
-        <module.install.skip>true</module.install.skip>
-        <module.deploy.skip>true</module.deploy.skip>
-    </properties>
-
     <dependencies>
         <dependency>
             <groupId>io.mosn.layotto</groupId>
@@ -51,24 +44,16 @@
         <plugins>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-install-plugin</artifactId>
-                <configuration>
-                    <skip>${module.install.skip}</skip>
-                </configuration>
-            </plugin>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-deploy-plugin</artifactId>
-                <configuration>
-                    <skip>${module.deploy.skip}</skip>
-                </configuration>
-            </plugin>
-            <plugin>
-                <groupId>org.apache.maven.plugins</groupId>
-                <artifactId>maven-surefire-plugin</artifactId>
-                <configuration>
-                    <skipTests>true</skipTests>
-                </configuration>
+                <artifactId>maven-source-plugin</artifactId>
+                <version>3.0.1</version>
+                <executions>
+                    <execution>
+                        <id>attach-sources</id>
+                        <goals>
+                            <goal>jar</goal>
+                        </goals>
+                    </execution>
+                </executions>
             </plugin>
         </plugins>
     </build>