Revert JRuby callback to use RubyBSONCallback

lib/bson/bson_java.rb

@@ -2,23 +2,17 @@ include Java
 module BSON
   class BSON_JAVA
 
+    # TODO: Pool or cache instances of RubyBSONEncoder so that
+    # we don't create a new one on each call to #serialize.
     def self.serialize(obj, check_keys=false, move_id=false)
       raise InvalidDocument, "BSON_JAVA.serialize takes a Hash" unless obj.is_a?(Hash)
       enc = Java::OrgJbson::RubyBSONEncoder.new(JRuby.runtime)
       ByteBuffer.new(enc.encode(obj))
     end
 
-    def self.get_encoder
-      @@enc ||= Java::OrgJbson::RubyBSONEncoder.new(JRuby.runtime)
-    end
-
-    def self.get_decoder
-      @@dec ||= Java::OrgBson::BSONDecoder.new
-    end
-
     def self.deserialize(buf)
       dec = Java::OrgBson::BSONDecoder.new
-      callback = Java::OrgJbson::RubyBSONJavaCallback.new(JRuby.runtime)
+      callback = Java::OrgJbson::RubyBSONCallback.new(JRuby.runtime)
       dec.decode(buf.to_s.to_java_bytes, callback)
       callback.get
     end