diff --git a/cartographer/mapping/submaps.h b/cartographer/mapping/submaps.h
index 840ad50..dd77f5a 100644
--- a/cartographer/mapping/submaps.h
+++ b/cartographer/mapping/submaps.h
@@ -67,25 +67,32 @@ class Submap {
                        bool include_probability_grid_data) const = 0;
   virtual void UpdateFromProto(const proto::Submap& proto) = 0;
 
+  // Fills data into the 'response'.
+  virtual void ToResponseProto(
+      const transform::Rigid3d& global_submap_pose,
+      proto::SubmapQuery::Response* response) const = 0;
+
   // Pose of this submap in the local map frame.
   transform::Rigid3d local_pose() const { return local_pose_; }
 
   // Number of RangeData inserted.
   int num_range_data() const { return num_range_data_; }
 
-  // Fills data into the 'response'.
-  virtual void ToResponseProto(
-      const transform::Rigid3d& global_submap_pose,
-      proto::SubmapQuery::Response* response) const = 0;
+  // Whether the submap is finished or not.
+  bool finished() const { return finished_; }
 
   void SetNumRangeData(const int num_range_data) {
     num_range_data_ = num_range_data;
   }
 
+  void SetFinished(bool finished) { finished_ = finished; }
+
  private:
   const transform::Rigid3d local_pose_;
   int num_range_data_ = 0;
+  bool finished_ = false;
 };
+
 }  // namespace mapping
 }  // namespace cartographer
 
diff --git a/cartographer/mapping_2d/submaps.cc b/cartographer/mapping_2d/submaps.cc
index aef515a..9fc5598 100644
--- a/cartographer/mapping_2d/submaps.cc
+++ b/cartographer/mapping_2d/submaps.cc
@@ -71,7 +71,7 @@ Submap::Submap(const mapping::proto::Submap2D& proto)
     : mapping::Submap(transform::ToRigid3(proto.local_pose())),
       probability_grid_(ProbabilityGrid(proto.probability_grid())) {
   SetNumRangeData(proto.num_range_data());
-  finished_ = proto.finished();
+  SetFinished(proto.finished());
 }
 
 void Submap::ToProto(mapping::proto::Submap* const proto,
@@ -79,7 +79,7 @@ void Submap::ToProto(mapping::proto::Submap* const proto,
   auto* const submap_2d = proto->mutable_submap_2d();
   *submap_2d->mutable_local_pose() = transform::ToProto(local_pose());
   submap_2d->set_num_range_data(num_range_data());
-  submap_2d->set_finished(finished_);
+  submap_2d->set_finished(finished());
   if (include_probability_grid_data) {
     *submap_2d->mutable_probability_grid() = probability_grid_.ToProto();
   }
@@ -89,7 +89,7 @@ void Submap::UpdateFromProto(const mapping::proto::Submap& proto) {
   CHECK(proto.has_submap_2d());
   const auto& submap_2d = proto.submap_2d();
   SetNumRangeData(submap_2d.num_range_data());
-  finished_ = submap_2d.finished();
+  SetFinished(submap_2d.finished());
   if (submap_2d.has_probability_grid()) {
     probability_grid_ = ProbabilityGrid(submap_2d.probability_grid());
   }
@@ -145,15 +145,15 @@ void Submap::ToResponseProto(
 
 void Submap::InsertRangeData(const sensor::RangeData& range_data,
                              const RangeDataInserter& range_data_inserter) {
-  CHECK(!finished_);
+  CHECK(!finished());
   range_data_inserter.Insert(range_data, &probability_grid_);
   SetNumRangeData(num_range_data() + 1);
 }
 
 void Submap::Finish() {
-  CHECK(!finished_);
+  CHECK(!finished());
   probability_grid_ = ComputeCroppedProbabilityGrid(probability_grid_);
-  finished_ = true;
+  SetFinished(true);
 }
 
 ActiveSubmaps::ActiveSubmaps(const proto::SubmapsOptions& options)
diff --git a/cartographer/mapping_2d/submaps.h b/cartographer/mapping_2d/submaps.h
index 04ed518..67da5d8 100644
--- a/cartographer/mapping_2d/submaps.h
+++ b/cartographer/mapping_2d/submaps.h
@@ -51,13 +51,12 @@ class Submap : public mapping::Submap {
                bool include_probability_grid_data) const override;
   void UpdateFromProto(const mapping::proto::Submap& proto) override;
 
-  const ProbabilityGrid& probability_grid() const { return probability_grid_; }
-  bool finished() const { return finished_; }
-
   void ToResponseProto(
       const transform::Rigid3d& global_submap_pose,
       mapping::proto::SubmapQuery::Response* response) const override;
 
+  const ProbabilityGrid& probability_grid() const { return probability_grid_; }
+
   // Insert 'range_data' into this submap using 'range_data_inserter'. The
   // submap must not be finished yet.
   void InsertRangeData(const sensor::RangeData& range_data,
@@ -66,7 +65,6 @@ class Submap : public mapping::Submap {
 
  private:
   ProbabilityGrid probability_grid_;
-  bool finished_ = false;
 };
 
 // Except during initialization when only a single submap exists, there are
diff --git a/cartographer/mapping_3d/submaps.cc b/cartographer/mapping_3d/submaps.cc
index 5a425d0..22acaea 100644
--- a/cartographer/mapping_3d/submaps.cc
+++ b/cartographer/mapping_3d/submaps.cc
@@ -212,7 +212,7 @@ Submap::Submap(const mapping::proto::Submap3D& proto)
       low_resolution_hybrid_grid_(
           common::make_unique<HybridGrid>(proto.low_resolution_hybrid_grid())) {
   SetNumRangeData(proto.num_range_data());
-  finished_ = proto.finished();
+  SetFinished(proto.finished());
 }
 
 void Submap::ToProto(mapping::proto::Submap* const proto,
@@ -220,7 +220,7 @@ void Submap::ToProto(mapping::proto::Submap* const proto,
   auto* const submap_3d = proto->mutable_submap_3d();
   *submap_3d->mutable_local_pose() = transform::ToProto(local_pose());
   submap_3d->set_num_range_data(num_range_data());
-  submap_3d->set_finished(finished_);
+  submap_3d->set_finished(finished());
   if (include_probability_grid_data) {
     *submap_3d->mutable_high_resolution_hybrid_grid() =
         high_resolution_hybrid_grid().ToProto();
@@ -233,7 +233,7 @@ void Submap::UpdateFromProto(const mapping::proto::Submap& proto) {
   CHECK(proto.has_submap_3d());
   const auto& submap_3d = proto.submap_3d();
   SetNumRangeData(submap_3d.num_range_data());
-  finished_ = submap_3d.finished();
+  SetFinished(submap_3d.finished());
   if (submap_3d.has_high_resolution_hybrid_grid()) {
     high_resolution_hybrid_grid_ =
         submap_3d.has_high_resolution_hybrid_grid()
@@ -264,7 +264,7 @@ void Submap::ToResponseProto(
 void Submap::InsertRangeData(const sensor::RangeData& range_data,
                              const RangeDataInserter& range_data_inserter,
                              const int high_resolution_max_range) {
-  CHECK(!finished_);
+  CHECK(!finished());
   const sensor::RangeData transformed_range_data = sensor::TransformRangeData(
       range_data, local_pose().inverse().cast<float>());
   range_data_inserter.Insert(
@@ -277,8 +277,8 @@ void Submap::InsertRangeData(const sensor::RangeData& range_data,
 }
 
 void Submap::Finish() {
-  CHECK(!finished_);
-  finished_ = true;
+  CHECK(!finished());
+  SetFinished(true);
 }
 
 ActiveSubmaps::ActiveSubmaps(const proto::SubmapsOptions& options)
diff --git a/cartographer/mapping_3d/submaps.h b/cartographer/mapping_3d/submaps.h
index d6635ee..51212f9 100644
--- a/cartographer/mapping_3d/submaps.h
+++ b/cartographer/mapping_3d/submaps.h
@@ -51,17 +51,16 @@ class Submap : public mapping::Submap {
                bool include_probability_grid_data) const override;
   void UpdateFromProto(const mapping::proto::Submap& proto) override;
 
+  void ToResponseProto(
+      const transform::Rigid3d& global_submap_pose,
+      mapping::proto::SubmapQuery::Response* response) const override;
+
   const HybridGrid& high_resolution_hybrid_grid() const {
     return *high_resolution_hybrid_grid_;
   }
   const HybridGrid& low_resolution_hybrid_grid() const {
     return *low_resolution_hybrid_grid_;
   }
-  bool finished() const { return finished_; }
-
-  void ToResponseProto(
-      const transform::Rigid3d& global_submap_pose,
-      mapping::proto::SubmapQuery::Response* response) const override;
 
   // Insert 'range_data' into this submap using 'range_data_inserter'. The
   // submap must not be finished yet.
@@ -73,7 +72,6 @@ class Submap : public mapping::Submap {
  private:
   std::unique_ptr<HybridGrid> high_resolution_hybrid_grid_;
   std::unique_ptr<HybridGrid> low_resolution_hybrid_grid_;
-  bool finished_ = false;
 };
 
 // Except during initialization when only a single submap exists, there are