8276337: Use override specifier in HeapDumper

Reviewed-by: stuefe, dholmes

src/hotspot/share/services/heapDumper.cpp

@@ -607,23 +607,23 @@ class DumpWriter : public AbstractDumpWriter {
  private:
   CompressionBackend _backend; // Does the actual writing.
  protected:
-  virtual void flush(bool force = false);
+  void flush(bool force = false) override;
 
  public:
   // Takes ownership of the writer and compressor.
   DumpWriter(AbstractWriter* writer, AbstractCompressor* compressor);
 
   // total number of bytes written to the disk
-  virtual julong bytes_written() const          { return (julong) _backend.get_written(); }
+  julong bytes_written() const override { return (julong) _backend.get_written(); }
 
-  virtual char const* error() const             { return _backend.error(); }
+  char const* error() const override    { return _backend.error(); }
 
   // Called by threads used for parallel writing.
   void writer_loop()                    { _backend.thread_loop(); }
   // Called when finish to release the threads.
-  virtual void deactivate()             { flush(); _backend.deactivate(); }
+  void deactivate() override            { flush(); _backend.deactivate(); }
   // Get the backend pointer, used by parallel dump writer.
-  CompressionBackend* backend_ptr() { return &_backend; }
+  CompressionBackend* backend_ptr()     { return &_backend; }
 
 };
 
@@ -701,7 +701,7 @@ class ParDumpWriter : public AbstractDumpWriter {
   bool _split_data;
   static const uint BackendFlushThreshold = 2;
  protected:
-  virtual void flush(bool force = false) {
+  void flush(bool force = false) override {
     assert(_pos != 0, "must not be zero");
     if (_pos != 0) {
       refresh_buffer();
@@ -742,8 +742,8 @@ class ParDumpWriter : public AbstractDumpWriter {
   }
 
   // total number of bytes written to the disk
-  virtual julong bytes_written() const          { return (julong) _backend_ptr->get_written(); }
-  virtual char const* error() const { return _err == NULL ? _backend_ptr->error() : _err; }
+  julong bytes_written() const override { return (julong) _backend_ptr->get_written(); }
+  char const* error() const override    { return _err == NULL ? _backend_ptr->error() : _err; }
 
   static void before_work() {
     assert(_lock == NULL, "ParDumpWriter lock must be initialized only once");
@@ -757,7 +757,7 @@ class ParDumpWriter : public AbstractDumpWriter {
   }
 
   // write raw bytes
-  virtual void write_raw(const void* s, size_t len) {
+  void write_raw(const void* s, size_t len) override {
     assert(!_in_dump_segment || (_sub_record_left >= len), "sub-record too large");
     debug_only(_sub_record_left -= len);
     assert(!_split_data, "Invalid split data");
@@ -778,7 +778,7 @@ class ParDumpWriter : public AbstractDumpWriter {
     set_position(position() + len);
   }
 
-  virtual void deactivate()             { flush(true); _backend_ptr->deactivate(); }
+  void deactivate() override { flush(true); _backend_ptr->deactivate(); }
 
  private:
   void allocate_internal_buffer() {