fixed classifier NPE

pom.xml

@@ -6,7 +6,7 @@
 
 	<groupId>com.inteligr8.alfresco</groupId>
 	<artifactId>amp-maven-plugin</artifactId>
-	<version>1.0-SNAPSHOT</version>
+	<version>1.1-SNAPSHOT</version>
 	<packaging>maven-plugin</packaging>
 
 	<name>A Maven plugin to generate AMP files</name>

src/main/java/com/inteligr8/alfresco/amp/AmpMojo.java

@@ -200,10 +200,18 @@ public class AmpMojo extends AbstractMojo implements ArtifactResolutionCallback
     }
     
     private File getModuleFile() throws MojoExecutionException {
+		if (this.classifier != null) {
+        	String moduleJarFile = this.injectClassifier(this.moduleJarFile);
+    		File jarFile = new File(moduleJarFile);
+    		if (jarFile.exists())
+				return jarFile;
+		}
+
     	File jarFile = new File(this.moduleJarFile);
-    	if (!jarFile.exists())
-    		throw new MojoExecutionException("The module JAR file does not exist: " + this.moduleJarFile);
-    	return jarFile;
+		if (jarFile.exists())
+			return jarFile;
+
+		throw new MojoExecutionException("The module JAR file does not exist: " + this.moduleJarFile);
     }
     
     private File getModulePropertyFile() throws MojoExecutionException {