WP_Theme_JSON::remove_keys_not_in_schema( array $tree, array $schema ): array

1860	protected static function remove_keys_not_in_schema( $tree, $schema ) {1861		if ( ! is_array( $tree ) ) {1862			return $tree;1863		}1864 1865		foreach ( $tree as $key => $value ) {1866			// Remove keys not in the schema or with null/empty values.1867			if ( ! array_key_exists( $key, $schema ) ) {1868				unset( $tree[ $key ] );1869				continue;1870			}1871 1872			// Validate type if schema specifies a boolean marker.1873			if ( is_bool( $schema[ $key ] ) ) {1874				// Schema expects a boolean value - validate the input matches.1875				if ( ! is_bool( $value ) ) {1876					unset( $tree[ $key ] );1877					continue;1878				}1879				// Type matches, keep the value and continue to next key.1880				continue;1881			}1882 1883			if ( is_array( $schema[ $key ] ) ) {1884				if ( ! is_array( $value ) ) {1885					unset( $tree[ $key ] );1886				} elseif ( wp_is_numeric_array( $value ) ) {1887					// If indexed, process each item in the array.1888					foreach ( $value as $item_key => $item_value ) {1889						if ( isset( $schema[ $key ][0] ) && is_array( $schema[ $key ][0] ) ) {1890							$tree[ $key ][ $item_key ] = self::remove_keys_not_in_schema( $item_value, $schema[ $key ][0] );1891						} else {1892							// If the schema does not define a further structure, keep the value as is.1893							$tree[ $key ][ $item_key ] = $item_value;1894						}1895					}1896				} else {1897					// If associative, process as a single object.1898					$tree[ $key ] = self::remove_keys_not_in_schema( $value, $schema[ $key ] );1899 1900					if ( empty( $tree[ $key ] ) ) {1901						unset( $tree[ $key ] );1902					}1903				}1904			}1905		}1906		return $tree;1907	}