FELIX-2820: Provide a default value when using <_wab/>

git-svn-id: https://svn.apache.org/repos/asf/felix/trunk@1139436 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/bundleplugin/src/main/java/org/apache/felix/bundleplugin/BundlePlugin.java b/bundleplugin/src/main/java/org/apache/felix/bundleplugin/BundlePlugin.java
index 76073bc..d9c9625 100644
--- a/bundleplugin/src/main/java/org/apache/felix/bundleplugin/BundlePlugin.java
+++ b/bundleplugin/src/main/java/org/apache/felix/bundleplugin/BundlePlugin.java
@@ -273,6 +273,12 @@
                 value = value.replaceAll( "\\p{Blank}*[\r\n]\\p{Blank}*", "" );
             }
 
+            if ( Analyzer.WAB.equals( key ) && value.length() == 0 )
+            {
+                // provide useful default
+                value = "src/main/webapp/";
+            }
+
             transformedInstructions.put( key, value );
         }
         return transformedInstructions;