code: @Override
      public void flushBuffer() throws IOException {
          if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) {
              Tr.debug(tc, "Flushing buffers: " + this);
          }
          if (null != this.outWriter) {
              this.outWriter.flush();
          } else {
              this.outStream.flush();
          }
      }
docs: /*
  @see javax.servlet.ServletResponse#flushBuffer()