Add option to omit "Created-By" manifest entry (#110)

This closes #110

Author: michael-o

src/main/java/org/codehaus/plexus/archiver/jar/JarArchiver.java

@@ -144,6 +144,11 @@ public class JarArchiver
      */
     private ArrayList<String> indexJars;
 
+    /**
+     * Creates a minimal default manifest with {@code Manifest-Version: 1.0} only.
+     */
+    private boolean minimalDefaultManifest = false;
+
     /**
      * constructor
      */
@@ -166,6 +171,15 @@ public void setIndex( boolean flag )
         index = flag;
     }
 
+    /**
+     * Set whether the default manifest is minimal, thus having only {@code Manifest-Version: 1.0} in it.
+     *
+     * @param minimalDefaultManifest true to create minimal default manifest
+     */
+    public void setMinimalDefaultManifest( boolean minimalDefaultManifest ) {
+        this.minimalDefaultManifest = minimalDefaultManifest;
+    }
+
     @SuppressWarnings(
     {
         "JavaDoc", "UnusedDeclaration"
@@ -331,7 +345,7 @@ protected boolean hasVirtualFiles()
     protected Manifest createManifest()
         throws ArchiverException
     {
-        Manifest finalManifest = Manifest.getDefaultManifest();
+        Manifest finalManifest = Manifest.getDefaultManifest( minimalDefaultManifest );
 
         if ( ( manifest == null ) && ( manifestFile != null ) )
         {

src/main/java/org/codehaus/plexus/archiver/jar/Manifest.java

@@ -755,31 +755,47 @@ public Iterator<String> iterator()
     /**
      * Construct a manifest from Ant's default manifest file.
      *
+     * @param minimalDefaultManifest
+     *            indicates whether a minimal manifest will be created, thus having only
+     *            {@code Manifest-Version: 1.0} in it.
+     *
      * @return the default manifest.
      *
-     * @throws ArchiverException if there is a problem loading the
-     * default manifest
+     * @throws ArchiverException
+     *             if there is a problem loading the default manifest
      */
-    public static Manifest getDefaultManifest()
+    public static Manifest getDefaultManifest( boolean minimalDefaultManifest )
         throws ArchiverException
     {
         final Manifest defaultManifest = new Manifest();
         defaultManifest.getMainAttributes().putValue( "Manifest-Version", "1.0" );
 
-        String createdBy = "Plexus Archiver";
+        if ( !minimalDefaultManifest )
+        {
+            String createdBy = "Plexus Archiver";
 
-        final String plexusArchiverVersion = JdkManifestFactory.getArchiverVersion();
+            final String plexusArchiverVersion = JdkManifestFactory.getArchiverVersion();
 
-        if ( plexusArchiverVersion != null )
-        {
-            createdBy += " " + plexusArchiverVersion;
-        }
+            if ( plexusArchiverVersion != null )
+            {
+                createdBy += " " + plexusArchiverVersion;
+            }
 
-        defaultManifest.getMainAttributes().putValue( "Created-By", createdBy );
+            defaultManifest.getMainAttributes().putValue( "Created-By", createdBy );
+        }
 
         return defaultManifest;
     }
 
+    /**
+     * @see #getDefaultManifest(boolean)
+     */
+    public static Manifest getDefaultManifest()
+        throws ArchiverException
+    {
+        return getDefaultManifest( false );
+    }
+
     /**
      * Construct an empty manifest
      */

src/test/java/org/codehaus/plexus/archiver/jar/ManifestTest.java

@@ -220,6 +220,11 @@ public void testGetDefaultManifest()
         assertEquals( 2, mainAttributes.size() );
         assertTrue( mainAttributes.containsKey( new java.util.jar.Attributes.Name( "Manifest-Version" ) ) );
         assertTrue( mainAttributes.containsKey( new java.util.jar.Attributes.Name( "Created-By" ) ) );
+
+        mf = Manifest.getDefaultManifest( true );
+        mainAttributes = mf.getMainAttributes();
+        assertEquals( 1, mainAttributes.size() );
+        assertTrue( mainAttributes.containsKey( new java.util.jar.Attributes.Name( "Manifest-Version" ) ) );
     }
 
     public void checkMultiLineAttribute( String in, String expected )