method Http2Session.close
Usage in Deno
```typescript import { type Http2Session } from "node:node__http2.d.ts"; ```
Http2Session.close(callback?: () => void): void
Gracefully closes the `Http2Session`, allowing any existing streams to
complete on their own and preventing new `Http2Stream` instances from being
created. Once closed, `http2session.destroy()`_might_ be called if there
are no open `Http2Stream` instances.
If specified, the `callback` function is registered as a handler for the`'close'` event.
void