# File lib/json-schema/attributes/additionalproperties.rb, line 29
      def self.remove_valid_properties(extra_properties, current_schema, validator)
        schema = current_schema.schema

        if schema['properties']
          extra_properties = extra_properties - schema['properties'].keys
        end

        if schema['patternProperties']
          schema['patternProperties'].each_key do |key|
            regexp = Regexp.new(key)
            extra_properties.reject! { |prop| regexp.match(prop) }
          end
        end

        if extended_schemas = schema['extends']
          extended_schemas = [extended_schemas] unless extended_schemas.is_a?(Array)
          extended_schemas.each do |schema_value|
            _, extended_schema = JSON::Schema::ExtendsAttribute.get_extended_uri_and_schema(schema_value, current_schema, validator)
            if extended_schema
              extra_properties = remove_valid_properties(extra_properties, extended_schema, validator)
            end
          end
        end

        extra_properties
      end