Block Locking: Register the 'lock' attribute on the server

lib/block-supports/lock.php

@@ -0,0 +1,35 @@
+<?php
+/**
+ * Spacing block support flag.
+ *
+ * Once 6.0 is the minimum supported WordPress version for the Gutenberg
+ * plugin, this shim can be removed
+ *
+ * @package gutenberg
+ */
+
+/**
+ * Registers the lock block attribute for block types.
+ *
+ * @param WP_Block_Type $block_type Block Type.
+ */
+function gutenberg_register_lock_support( $block_type ) {
+	// Setup attributes if needed.
+	if ( ! $block_type->attributes ) {
+		$block_type->attributes = array();
+	}
+
+	if ( ! array_key_exists( 'lock', $block_type->attributes ) ) {
+		$block_type->attributes['lock'] = array(
+			'type' => 'object',
+		);
+	}
+}
+
+// Register the block support.
+WP_Block_Supports::get_instance()->register(
+	'lock',
+	array(
+		'register_attribute' => 'gutenberg_register_lock_support',
+	)
+);

lib/load.php

@@ -145,6 +145,7 @@ function gutenberg_is_experiment_enabled( $name ) {
 require __DIR__ . '/block-supports/typography.php';
 require __DIR__ . '/block-supports/border.php';
 require __DIR__ . '/block-supports/layout.php';
+require __DIR__ . '/block-supports/lock.php';
 require __DIR__ . '/block-supports/spacing.php';
 require __DIR__ . '/block-supports/dimensions.php';
 require __DIR__ . '/block-supports/duotone.php';