Add missing javadoc to bitmap index classes

Change-Id: Ib9fd230c9465a719df53cfcb314d8b5015743928
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit/src/org/eclipse/jgit/internal/storage/file/BitmapIndexImpl.java

@@ -327,6 +327,12 @@ public class BitmapIndexImpl implements BitmapIndex {
 		final EWAHCompressedBitmap bitmap;
 		final BitmapIndexImpl bitmapIndex;
 
+		/**
+		 * Construct compressed bitmap for given bitmap and bitmap index
+		 *
+		 * @param bitmap
+		 * @param bitmapIndex
+		 */
 		public CompressedBitmap(EWAHCompressedBitmap bitmap, BitmapIndexImpl bitmapIndex) {
 			this.bitmap = bitmap;
 			this.bitmapIndex = bitmapIndex;

org.eclipse.jgit/src/org/eclipse/jgit/lib/BitmapIndex.java

@@ -206,7 +206,9 @@ public interface BitmapIndex {
 		int cardinality();
 
 		/**
-		 * The BitmapIndex for this BitmapBuilder.
+		 * Get the BitmapIndex for this BitmapBuilder.
+		 *
+		 * @return the BitmapIndex for this BitmapBuilder
 		 *
 		 * @since 4.2
 		 */