encode method Null safety

Implementation

@override
void encode(KeyedArchive object) {
  super.encode(object);

  object.encode("title", title);
  object.encode("maximum", maximum);
  object.encode("exclusiveMaximum", exclusiveMaximum);
  object.encode("minimum", minimum);
  object.encode("exclusiveMinimum", exclusiveMinimum);
  object.encode("maxLength", maxLength);
  object.encode("minLength", minLength);
  object.encode("pattern", pattern);
  object.encode("maxItems", maxItems);
  object.encode("minItems", minItems);
  object.encode("uniqueItems", uniqueItems);
  object.encode("multipleOf", multipleOf);
  object.encode("enum", enumerated);
  object.encode("minProperties", minProperties);
  object.encode("maxProperties", maxProperties);
  object.encode("required", isRequired);

  //

  object.encode("type", APITypeCodec.encode(type));
  object.encodeObjects("allOf", allOf);
  object.encodeObjects("anyOf", anyOf);
  object.encodeObjects("oneOf", oneOf);
  object.encodeObject("not", not);

  object.encodeObject("items", items);
  if (additionalPropertyPolicy != null || additionalPropertySchema != null) {
    if (additionalPropertyPolicy ==
        APISchemaAdditionalPropertyPolicy.disallowed) {
      object.encode("additionalProperties", false);
    } else if (additionalPropertyPolicy ==
        APISchemaAdditionalPropertyPolicy.freeForm) {
      object.encode("additionalProperties", true);
    } else {
      object.encodeObject("additionalProperties", additionalPropertySchema);
    }
  }
  object.encodeObjectMap("properties", properties);

  object.encode("description", description);
  object.encode("format", format);
  object.encode("default", defaultValue);

  object.encode("nullable", _nullable);
  object.encode("readOnly", _readOnly);
  object.encode("writeOnly", _writeOnly);
  object.encode("deprecated", deprecated);
}