Use maven-antrun-plugin instead of exec-maven-plugin

Motivation:

exec-maven-plugin does not flush stdout and stderr, making the console
output from the examples invisible to users

Modification:

Use maven-antrun-plugin instead

Result:

A user sees the output from the examples immediately.

all/pom.xml

@@ -292,7 +292,7 @@
             <goals>
               <goal>run</goal>
             </goals>
-            <configuration>
+            <configuration combine.self="override">
               <target>
                 <taskdef resource="net/sf/antcontrib/antlib.xml" />
                 <propertyselector property="versions" match="^(${project.groupId}:(?!netty-example)[^:]+:jar)$" select="\1" />

example/pom.xml

@@ -104,20 +104,17 @@
   <build>
     <plugins>
       <plugin>
-        <groupId>org.codehaus.mojo</groupId>
-        <artifactId>exec-maven-plugin</artifactId>
+        <artifactId>maven-antrun-plugin</artifactId>
         <configuration>
-          <executable>${java.home}/bin/java</executable>
-          <commandlineArgs>
-            ${argLine.common}
-            ${argLine.bootcp}
-            ${argLine.leak}
-            ${argLine.coverage}
-            -classpath %classpath
-            ${argLine.example}
-            ${exampleClass}
-          </commandlineArgs>
-          <classpathScope>runtime</classpathScope>
+          <target>
+            <taskdef resource="net/sf/antcontrib/antlib.xml" />
+            <propertyregex
+              property="mergedArgs" regexp="[\r\n\s]+" replace=" " global="true"
+              input="${argLine.common} ${argLine.bootcp} ${argLine.leak} ${argLine.coverage} ${argLine.example}" />
+            <java classname="${exampleClass}" classpathref="maven.runtime.classpath" fork="true">
+              <jvmarg line="${mergedArgs}"/>
+            </java>
+          </target>
         </configuration>
       </plugin>
     </plugins>

pom.xml

@@ -857,7 +857,7 @@
             <goals>
               <goal>run</goal>
             </goals>
-            <configuration>
+            <configuration combine.self="override">
               <target>
                 <taskdef resource="net/sf/antcontrib/antlib.xml" />
 
@@ -1065,11 +1065,6 @@
           <artifactId>build-helper-maven-plugin</artifactId>
           <version>1.8</version>
         </plugin>               
-        <plugin>
-          <groupId>org.codehaus.mojo</groupId>
-          <artifactId>exec-maven-plugin</artifactId>
-          <version>1.3</version>
-        </plugin>
         <plugin>
           <groupId>org.fusesource.hawtjni</groupId>
           <artifactId>maven-hawtjni-plugin</artifactId>

run-example.sh

@@ -58,5 +58,5 @@ fi
 
 cd "`dirname "$0"`"/example
 echo "[INFO] Running: $EXAMPLE ($EXAMPLE_CLASS $EXAMPLE_ARGS)"
-exec mvn -nsu compile exec:exec -DargLine.example="$EXAMPLE_ARGS" -DexampleClass="$EXAMPLE_CLASS"
+exec mvn -nsu compile antrun:run -Dcheckstyle.skip=true -Dantfile=src/antrun/run-example.xml -DargLine.example="$EXAMPLE_ARGS" -DexampleClass="$EXAMPLE_CLASS"