Source

File: wp-includes/class-wp-block-pattern-categories-registry.php

public function register( $category_name, $category_properties ) {
		if ( ! isset( $category_name ) || ! is_string( $category_name ) ) {
			_doing_it_wrong( __METHOD__, __( 'Block pattern category name must be a string.' ), '5.5.0' );
			return false;
		}

		$this->registered_categories[ $category_name ] = array_merge(
			array( 'name' => $category_name ),
			$category_properties
		);

		return true;
	}