LUCENE-4837: Expose buffer size in BufferedIndexOutput

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1457211 13f79535-47bb-0310-9956-ffa450edef68

lucene/core/src/java/org/apache/lucene/store/BufferedIndexOutput.java

@@ -133,6 +133,12 @@ public abstract class BufferedIndexOutput extends IndexOutput {
 
   @Override
   public abstract long length() throws IOException;
-
+  
+  /**
+   * Returns size of the used output buffer in bytes.
+   * */
+  public final int getBufferSize() {
+    return bufferSize;
+  }
 
 }