bp_core_get_avatar_data_url_filter( string $retval, mixed $id_or_email, array $args )

function bp_core_get_avatar_data_url_filter( $retval, $id_or_email, $args ) {
	$user = null;

	// Added this check for the display proper images in /wp-admin/options-discussion.php page Default Avatar page.
	global $pagenow;
	if ( 'options-discussion.php' === $pagenow ) {
		if ( true === $args["force_default"] && 'mm' === $args["default"] ) {
			return buddypress()->plugin_url . 'bp-core/images/mystery-man-50.jpg';
		} else if ( true === $args["force_default"] ) {
			return $retval;
		}
	}

	// Ugh, hate duplicating code; process the user identifier.
	if ( is_numeric( $id_or_email ) ) {
		$user = get_user_by( 'id', absint( $id_or_email ) );
	} elseif ( $id_or_email instanceof WP_User ) {
		// User Object
		$user = $id_or_email;
	} elseif ( $id_or_email instanceof WP_Post ) {
		// Post Object
		$user = get_user_by( 'id', (int) $id_or_email->post_author );
	} elseif ( $id_or_email instanceof WP_Comment ) {
		if ( ! empty( $id_or_email->user_id ) ) {
			$user = get_user_by( 'id', (int) $id_or_email->user_id );
		}
	} elseif ( is_email( $id_or_email ) ) {
		$user = get_user_by( 'email', $id_or_email );
	}

	// No user, so bail.
	if ( false === $user instanceof WP_User ) {
		return $retval;
	}

	// Set BuddyPress-specific avatar args.
	$args['item_id'] = $user->ID;
	$args['html']    = false;

	// Use the 'full' type if size is larger than BP's thumb width.
	if ( (int) $args['size'] > bp_core_avatar_thumb_width() ) {
		$args['type'] = 'full';
	}

	// Get the BuddyPress avatar URL.
	if ( $bp_avatar = bp_core_fetch_avatar( $args ) ) {
		return $bp_avatar;
	}

	return $retval;
}