def METHOD_NAME(self) -> Dict[str, Any]:
    environ = super().METHOD_NAME()
    # From pallets/werkzeug#1469, will probably be in release after
    # 0.16.0.
    try:
        # binary_form=False gives nicer information, but wouldn't be
        # compatible with what Nginx or Apache could return.
        peer_cert = self.connection.getpeercert(binary_form=True)
        if peer_cert is not None:
            # Nginx and Apache use PEM format.
            environ["SSL_CLIENT_CERT"] = ssl.DER_cert_to_PEM_cert(
                peer_cert,
            )
    except ValueError:
        # SSL handshake hasn't finished.
        self.server.log("error", "Cannot fetch SSL peer certificate info")
    except AttributeError:
        # Not using TLS, the socket will not have getpeercert().
        pass
    return environ