public function merge_array( $config ) {
		foreach ( $this->spec as $key => $details ) {
			if ( false !== $details['runtime'] && isset( $config[ $key ] ) ) {
				$value = $config[ $key ];

				if ( 'require' === $key ) {
					$value = \WP_CLI\Utils\expand_globs( $value );
				}

				if ( $details['multiple'] ) {
					self::arrayify( $value );
					$this->config[ $key ] = array_merge( $this->config[ $key ], $value );
				} else {
					$this->config[ $key ] = $value;
				}
			}
		}
	}