Simplify RestModifyView interface

The inputType can be determined by looking at the declaration
of the interface. We don't need to implement a method in each
view implementation to supply the correct data for reflection
in RestApiServlet.

Change-Id: I1afae6ddef661722efe39ccc917c028e7e993595

gerrit-server/src/main/java/com/google/gerrit/server/change/DeleteReviewer.java

@@ -43,11 +43,6 @@ class DeleteReviewer implements RestModifyView<ReviewerResource, Input> {
     this.dbProvider = dbProvider;
   }
 
-  @Override
-  public Class<Input> inputType() {
-    return Input.class;
-  }
-
   @Override
   public Object apply(ReviewerResource rsrc, Input input)
       throws AuthException, ResourceNotFoundException, OrmException {