Automattic / jetpack

			if ( in_array( $key, array( 'HTTP_COOKIE', 'HTTP_COOKIE2', 'HTTP_USER_AGENT', 'HTTP_REFERER' ) ) ) {

				// We don't care about cookies, and the UA and Referrer were caught above.

				continue;

			} elseif ( in_array( $key, array( 'REMOTE_ADDR', 'REQUEST_URI', 'DOCUMENT_URI' ) ) ) {

				// All three of these are relevant indicators and should be passed along.

				$form[ $key ] = $value;

			} elseif ( wp_startswith( $key, 'HTTP_' ) ) {

				// Any other HTTP header indicators.

				// `wp_startswith()` is a wpcom helper function and is included in Jetpack via `functions.compat.php`

				$form[ $key ] = $value;

		if ( 0 === strpos( $key, 'HTTP_' ) ) {

			$data[ $key ] = $value; // HTTP headers.

		} elseif ( in_array( $key, array( 'REMOTE_ADDR', 'REQUEST_URI', 'DOCUMENT_URI' ), true ) ) {

			$data[ $key ] = $value;

		}

	}

	return $data;