Use empty BufferPool for EC reconstruction

      // TODO: Let's avoid unnecessary bufferPool creation. This pool actually
      //  not used in EC flows, but there are some dependencies on buffer pool.
      BufferPool bufferPool =
          new BufferPool(configuration.getStreamBufferSize(),
              (int) (configuration.getStreamBufferMaxSize() / configuration
                  .getStreamBufferSize()),
              ByteStringConversion.createByteBufferConversion(false));