Include Bundlor-generated manifests in jars

In the 2.0.0.M5 release bundlor successfully created manifests at
target/classes/META-INF/MANIFEST.MF within each subproject directory,
however they were not actually picked up by the maven-jar-plugin when
creating each archive. The samples parent pom has now been configured
to explictly specify the 'manifestFile' and refer to the bundlor-generated
manifest.

Additionally, the spring-integration-samples/pom.xml was updated with
a similar configuration for the maven-jar-plugin, but in this case the
spring-integration-parent/pom.xml configuration is being overwritten.
The samples projects do not use Bundlor, and thus there is no generated
manifest in the location mentioned above. This causes the maven-jar-plugin
to error out for the samples, and as a workaround there is now a zero-length
file at spring-integration-samples/src/main/resources/META-INF/MANIFEST.MF
that samples refer to during jar/war packaging. Ugly, but effective.

spring-integration-parent/pom.xml

@@ -355,6 +355,17 @@
 						</execution>
 					</executions>
 				</plugin>
+				<plugin><!--
+					configures the jar plugin to pick up the manifest created by bundlor (see above) -->
+					<groupId>org.apache.maven.plugins</groupId>
+					<artifactId>maven-jar-plugin</artifactId>
+					<version>2.2</version>
+					<configuration>
+						<archive>
+							<manifestFile>target/classes/META-INF/MANIFEST.MF</manifestFile>
+						</archive>
+					</configuration>
+				</plugin>
 			</plugins>
 		</pluginManagement>
 	</build>

spring-integration-samples/pom.xml

@@ -27,6 +27,23 @@
 		<module>ws-outbound-gateway</module>
 		<module>xml</module>
 	</modules>
+	<build>
+		<plugins>
+			<plugin><!--
+				overrides jar plugin configuration in parent pom that looks for
+				a bundlor-generated MANIFEST.MF.  The manifest specified here
+				is intentionally empty. -->
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-jar-plugin</artifactId>
+				<version>2.2</version>
+				<configuration>
+					<archive>
+						<manifestFile>../src/main/resources/META-INF/MANIFEST.MF</manifestFile>
+					</archive>
+				</configuration>
+			</plugin>
+		</plugins>
+	</build>
 	<dependencyManagement>
 		<dependencies>
 			<dependency>