add toString, equals, and hashCode to BitmapSerdeFactory

processing/src/main/java/io/druid/segment/data/ConciseBitmapSerdeFactory.java

@@ -97,4 +97,22 @@ public class ConciseBitmapSerdeFactory implements BitmapSerdeFactory
       return conciseComparator.compare((WrappedImmutableConciseBitmap) o1, (WrappedImmutableConciseBitmap) o2);
     }
   }
+
+  @Override
+  public String toString()
+  {
+    return "ConciseBitmapSerdeFactory{}";
+  }
+
+  @Override
+  public boolean equals(Object o)
+  {
+    return this == o || o instanceof ConciseBitmapSerdeFactory;
+  }
+
+  @Override
+  public int hashCode()
+  {
+    return 0;
+  }
 }

processing/src/main/java/io/druid/segment/data/RoaringBitmapSerdeFactory.java

@@ -98,4 +98,22 @@ public class RoaringBitmapSerdeFactory implements BitmapSerdeFactory
       return roaringComparator.compare((WrappedImmutableRoaringBitmap) o1, (WrappedImmutableRoaringBitmap) o2);
     }
   }
+
+  @Override
+  public String toString()
+  {
+    return "RoaringBitmapSerdeFactory{}";
+  }
+
+  @Override
+  public boolean equals(Object o)
+  {
+    return this == o || o instanceof RoaringBitmapSerdeFactory;
+  }
+
+  @Override
+  public int hashCode()
+  {
+    return 0;
+  }
 }