code: @FFDCIgnore({ IOException.class })
      private void convertFile(FileChannel fc) throws IOException {
          if (TraceComponent.isAnyTracingEnabled() && tc.isEventEnabled()) {
              Tr.event(tc, "Converting FileChannel to buffers");
          }
          final WsByteBuffer[] body = new WsByteBuffer[1];
          final WsByteBufferPoolManager mgr = HttpDispatcher.getBufferManager();
          final long max = fc.size();
          final long blocksize = (1048576L < max) ? 1048576L : max;
          long offset = 0;
          while (offset < max) {
              ByteBuffer bb = fc.map(MapMode.READ_ONLY, offset, blocksize);
              offset += blocksize;
              WsByteBuffer wsbb = mgr.wrap(bb);
              body[0] = wsbb;
              try {
                  this.isc.sendResponseBody(body);
              } catch (MessageSentException mse) {
                  FFDCFilter.processException(mse, getClass().getName(),
                                              "convertFile", new Object[] { this, this.isc });
                  if (TraceComponent.isAnyTracingEnabled() && tc.isEventEnabled()) {
                      Tr.event(tc, "Invalid state, message-sent-exception received; " + this.isc);
                  }
                  this.error = new IOException("Invalid state");
                  throw this.error;
              } catch (IOException ioe) {
                  // no FFDC required
                  this.error = ioe;
                  if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) {
                      Tr.debug(tc, "Received exception during write: " + ioe);
                  }
                  throw ioe;
              } finally {
                  wsbb.release();
              }
          } // end-while
      }
docs: User attempted to use the optimized FileChannel writing; however, that
  path is currently disabled. This method will read the file and do repeated
  write calls until done. This avoids TCP channel doing it in one big block.
  
  @param fc
  @throws IOException